tooltip.find('.saved .message .query-vs').click(function(event) {

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enforce a maximum line length (max-len)

Very long lines of code in any language can be difficult to read. In order to aid in readability and maintainability many coders have developed a convention to limit lines of code to X number of characters (traditionally 80 characters).

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // very long

Rule Details

This rule enforces a maximum line length to increase code readability and maintainability.

Note: This rule calculates the length of a line via code points, not characters. That means if you use a double-byte character in your code, it will count as 2 code points instead of 1, and 2 will be used to calculate line length. This is a technical limitation of JavaScript that is made easier with ES2015, and we will look to update this when ES2015 is available in Node.js.

Options

This rule has a number or object option:

• "code" (default 80) enforces a maximum line length
• "tabWidth" (default 4) specifies the character width for tab characters
• "comments" enforces a maximum line length for comments; defaults to value of code
• "ignorePattern" ignores lines matching a regular expression; can only match a single line and need to be double escaped when written in YAML or JSON
• "ignoreComments": true ignores all trailing comments and comments on their own line
• "ignoreTrailingComments": true ignores only trailing comments
• "ignoreUrls": true ignores lines that contain a URL

code

Examples of incorrect code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" };

Examples of correct code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = {
  "bar": "This is a bar.",
  "baz": { "qux": "This is a qux" },
  "easier": "to read"
};

tabWidth

Examples of incorrect code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" } };

Examples of correct code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = {
\t  \t  \t  \t  "bar": "This is a bar.",
\t  \t  \t  \t  "baz": { "qux": "This is a qux" }
\t  \t  };

comments

Examples of incorrect code for this rule with the { "comments": 65 } option:

/*eslint max-len: ["error", { "comments": 65 }]*/

/**
 * This is a comment that violates the maximum line length we have specified
**/

ignoreComments

Examples of correct code for this rule with the { "ignoreComments": true } option:

/*eslint max-len: ["error", { "ignoreComments": true }]*/

/**
 * This is a really really really really really really really really really long comment
**/

ignoreTrailingComments

Examples of correct code for this rule with the { "ignoreTrailingComments": true } option:

/*eslint max-len: ["error", { "ignoreTrailingComments": true }]*/

var foo = 'bar'; // This is a really really really really really really really long comment

ignoreUrls

Examples of correct code for this rule with the { "ignoreUrls": true } option:

/*eslint max-len: ["error", { "ignoreUrls": true }]*/

var url = 'https://www.example.com/really/really/really/really/really/really/really/long';

ignorePattern

Examples of correct code for this rule with the { "ignorePattern": true } option:

/*eslint max-len: ["error", { "ignorePattern": "^\\s*var\\s.+=\\s*require\\s*\\(/" }]*/

var dep = require('really/really/really/really/really/really/really/really/long/module');

Related Rules

• [complexity](complexity.md)
• [max-depth](max-depth.md)
• [max-nested-callbacks](max-nested-callbacks.md)
• [max-params](max-params.md)
• [max-statements](max-statements.md) Source: http://eslint.org/docs/rules/

                $("body").append(temp);

Close

Enforce Quote Style (quotes)

(fixable) The --fix option on the [command line](../user-guide/command-line-interface#fix) automatically fixes problems reported by this rule.

JavaScript allows you to define strings in one of three ways: double quotes, single quotes, and backticks (as of ECMAScript 6). For example:

/*eslint-env es6*/

var double = "double";
var single = 'single';
var backtick = `backtick`;    // ES6 only

Each of these lines creates a string and, in some cases, can be used interchangeably. The choice of how to define strings in a codebase is a stylistic one outside of template literals (which allow embedded of expressions to be interpreted).

Many codebases require strings to be defined in a consistent manner.

Rule Details

This rule is aimed at ensuring consistency of string quotes and as such will report a problem when an inconsistent style is found.

The rule configuration takes up to two options:

1. The first option is "double", "single" or "backtick" for double-quotes, single-quotes or backticks respectively. The default is "double".
2. The second option takes two options:
   1. "avoidEscape": When using "avoidEscape", this rule will not report a problem when a string is using single-quotes or double-quotes so long as the string contains a quote that would have to be escaped otherwise. For example, if you specify "double" and "avoidEscape", the string 'He said, "hi!"' is not considered a problem because using double quotes for that string would require escaping the double quotes inside of the string. This option is off by default.
   2. "allowTemplateLiterals": when using "allowTemplateLiterals", this rule will not report a problem when a string is using backticks and option one is either "double" or "single".

When using "single" or "double", template literals that don't contain a substitution, don't contain a line break and aren't tagged templates, are flagged as problems, even with the "avoidEscape" option. However they are not problems when "allowTemplateLiterals" is used.

Configuration looks like this:

[2, "single", {"avoidEscape": true, "allowTemplateLiterals": true}]

Deprecation notice: The avoid-escape option is a deprecated syntax and you should use the object form instead.

The following patterns are considered problems:

/*eslint quotes: ["error", "double"]*/

var single = 'single';
var unescaped = 'a string containing "double" quotes';

/*eslint quotes: ["error", "single"]*/

var double = "double";
var unescaped = "a string containing 'single' quotes";

/*eslint quotes: ["error", "double", {"avoidEscape": true}]*/

var single = 'single';
var single = `single`;

/*eslint quotes: ["error", "single", {"avoidEscape": true}]*/

var double = "double";
var double = `double`;

/*eslint quotes: ["error", "backtick"]*/

var single = 'single';
var double = "double";
var unescaped = 'a string containing `backticks`';

/*eslint quotes: ["error", "backtick", {"avoidEscape": true}]*/

var single = 'single';
var double = "double";

The following patterns are not considered problems:

/*eslint quotes: ["error", "double"]*/
/*eslint-env es6*/

var double = "double";
var backtick = `back\ntick`;  // backticks are allowed due to newline
var backtick = tag`backtick`; // backticks are allowed due to tag

/*eslint quotes: ["error", "single"]*/
/*eslint-env es6*/

var single = 'single';
var backtick = `back${x}tick`; // backticks are allowed due to substitution

/*eslint quotes: ["error", "double", {"avoidEscape": true}]*/

var single = 'a string containing "double" quotes';

/*eslint quotes: ["error", "single", {"avoidEscape": true}]*/

var double = "a string containing 'single' quotes";

/*eslint quotes: ["error", "double", {"allowTemplateLiterals": true}]*/

var single = 'single';
var single = `single`;

/*eslint quotes: ["error", "single", {"allowTemplateLiterals": true}]*/

var double = "double";
var double = `double`;

/*eslint quotes: ["error", "backtick"]*/
/*eslint-env es6*/

var backtick = `backtick`;

/*eslint quotes: ["error", "backtick", {"avoidEscape": true}]*/

var double = "a string containing `backtick` quotes"

When Not To Use It

If you do not need consistency in your string styles, you can safely disable this rule. Source: http://eslint.org/docs/rules/

        $.when(window.iviz.datamanager.getClinicalData(_attrIds, (_type === 'patient')))

Close

enforce a maximum line length (max-len)

Very long lines of code in any language can be difficult to read. In order to aid in readability and maintainability many coders have developed a convention to limit lines of code to X number of characters (traditionally 80 characters).

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // very long

Rule Details

This rule enforces a maximum line length to increase code readability and maintainability.

Note: This rule calculates the length of a line via code points, not characters. That means if you use a double-byte character in your code, it will count as 2 code points instead of 1, and 2 will be used to calculate line length. This is a technical limitation of JavaScript that is made easier with ES2015, and we will look to update this when ES2015 is available in Node.js.

Options

This rule has a number or object option:

• "code" (default 80) enforces a maximum line length
• "tabWidth" (default 4) specifies the character width for tab characters
• "comments" enforces a maximum line length for comments; defaults to value of code
• "ignorePattern" ignores lines matching a regular expression; can only match a single line and need to be double escaped when written in YAML or JSON
• "ignoreComments": true ignores all trailing comments and comments on their own line
• "ignoreTrailingComments": true ignores only trailing comments
• "ignoreUrls": true ignores lines that contain a URL

code

Examples of incorrect code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" };

Examples of correct code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = {
  "bar": "This is a bar.",
  "baz": { "qux": "This is a qux" },
  "easier": "to read"
};

tabWidth

Examples of incorrect code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" } };

Examples of correct code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = {
\t  \t  \t  \t  "bar": "This is a bar.",
\t  \t  \t  \t  "baz": { "qux": "This is a qux" }
\t  \t  };

comments

Examples of incorrect code for this rule with the { "comments": 65 } option:

/*eslint max-len: ["error", { "comments": 65 }]*/

/**
 * This is a comment that violates the maximum line length we have specified
**/

ignoreComments

Examples of correct code for this rule with the { "ignoreComments": true } option:

/*eslint max-len: ["error", { "ignoreComments": true }]*/

/**
 * This is a really really really really really really really really really long comment
**/

ignoreTrailingComments

Examples of correct code for this rule with the { "ignoreTrailingComments": true } option:

/*eslint max-len: ["error", { "ignoreTrailingComments": true }]*/

var foo = 'bar'; // This is a really really really really really really really long comment

ignoreUrls

Examples of correct code for this rule with the { "ignoreUrls": true } option:

/*eslint max-len: ["error", { "ignoreUrls": true }]*/

var url = 'https://www.example.com/really/really/really/really/really/really/really/long';

ignorePattern

Examples of correct code for this rule with the { "ignorePattern": true } option:

/*eslint max-len: ["error", { "ignorePattern": "^\\s*var\\s.+=\\s*require\\s*\\(/" }]*/

var dep = require('really/really/really/really/really/really/really/really/long/module');

Related Rules

• [complexity](complexity.md)
• [max-depth](max-depth.md)
• [max-nested-callbacks](max-nested-callbacks.md)
• [max-params](max-params.md)
• [max-statements](max-statements.md) Source: http://eslint.org/docs/rules/

          tableData_.cna_details.allSamples.push({

Close

Quoting Style for Property Names (quote-props)

Object literal property names can be defined in two ways: using literals or using strings. For example, these two objects are equivalent:

var object1 = {
    property: true
};

var object2 = {
    "property": true
};

In many cases, it doesn't matter if you choose to use an identifier instead of a string or vice-versa. Even so, you might decide to enforce a consistent style in your code.

There are, however, some occasions when you must use quotes:

1. If you are using an ECMAScript 3 JavaScript engine (such as IE8) and you want to use a keyword (such as if) as a property name. This restriction was removed in ECMAScript 5.
2. You want to use a non-identifier character in your property name, such as having a property with a space like "one two".

Another example where quotes do matter is when using numeric literals as property keys:

var object = {
    1e2: 1,
    100: 2
};

This may look alright at first sight, but this code in fact throws a syntax error in ECMAScript 5 strict mode. This happens because 1e2 and 100 are coerced into strings before getting used as the property name. Both String(1e2) and String(100) happen to be equal to "100", which causes the "Duplicate data property in object literal not allowed in strict mode" error. Issues like that can be tricky to debug, so some prefer to require quotes around all property names.

Rule Details

This rule aims to enforce use of quotes in property names and as such will flag any properties that don't use quotes (default behavior).

Options

There are four behaviors for this rule: "always" (default), "as-needed", "consistent" and "consistent-as-needed". You can define these options in your configuration as:

{
    "quote-props": ["error", "as-needed"]
}

"always"

When configured with "always" as the first option (the default), quoting for all properties will be enforced. Some believe that ensuring property names in object literals are always wrapped in quotes is generally a good idea, since depending on the property name you may need to quote them anyway. Consider this example:

var object = {
    foo: "bar",
    baz: 42,
    "qux-lorem": true
};

Here, the properties foo and baz are not wrapped in quotes, but qux-lorem is, because it doesn’t work without the quotes. This is rather inconsistent. Instead, you may prefer to quote names of all properties:

var object = {
    "foo": "bar",
    "baz": 42,
    "qux-lorem": true
};

or, if you prefer single quotes:

var object = {
    'foo': 'bar',
    'baz': 42,
    'qux-lorem': true
};

When configured with "always" as the first option (the default), quoting for all properties will be enforced. The following patterns are considered problems:

/*eslint quote-props: ["error", "always"]*/

var object = {
    foo: "bar",
    baz: 42,
    "qux-lorem": true
};

The following patterns are not considered problems:

/*eslint quote-props: ["error", "always"]*/
/*eslint-env es6*/

var object1 = {
    "foo": "bar",
    "baz": 42,
    "qux-lorem": true
};

var object2 = {
    'foo': 'bar',
    'baz': 42,
    'qux-lorem': true
};

var object3 = {
    foo() {
        return;
    }
};

"as-needed"

When configured with "as-needed" as the first option, quotes will be enforced when they are strictly required, and unnecessary quotes will cause warnings. The following patterns are considered problems:

/*eslint quote-props: ["error", "as-needed"]*/

var object = {
    "a": 0,
    "0": 0,
    "true": 0,
    "null": 0
};

The following patterns are not considered problems:

/*eslint quote-props: ["error", "as-needed"]*/
/*eslint-env es6*/

var object1 = {
    "a-b": 0,
    "0x0": 0,
    "1e2": 0
};

var object2 = {
    foo: 'bar',
    baz: 42,
    true: 0,
    0: 0,
    'qux-lorem': true
};

var object3 = {
    foo() {
        return;
    }
};

When the "as-needed" mode is selected, an additional keywords option can be provided. This flag indicates whether language keywords should be quoted as properties. By default it is set to false.

{
    "quote-props": ["error", "as-needed", { "keywords": true }]
}

When keywords is set to true, the following patterns become problems:

/*eslint quote-props: ["error", "as-needed", { "keywords": true }]*/

var x = {
    while: 1,
    volatile: "foo"
};

Another modifier for this rule is the unnecessary option which defaults to true. Setting this to false will prevent the rule from complaining about unnecessarily quoted properties. This comes in handy when you only care about quoting keywords.

{
    "quote-props": ["error", "as-needed", { "keywords": true, "unnecessary": false }]
}

When unnecessary is set to false, the following patterns stop being problems:

/*eslint quote-props: ["error", "as-needed", { "keywords": true, "unnecessary": false }]*/

var x = {
    "while": 1,
    "foo": "bar"  // Would normally have caused a warning
};

A numbers flag, with default value false, can also be used as a modifier for the "as-needed" mode. When it is set to true, numeric literals should always be quoted.

{
    "quote-props": ["error", "as-needed", {"numbers": true}]
}

When numbers is set to true, the following patterns become problems:

/*eslint quote-props: ["error", "as-needed", { "numbers": true }]*/

var x = {
    100: 1
}

and the following patterns stop being problems:

var x = {
    "100": 1
}

"consistent"

When configured with "consistent", the patterns below are considered problems. Basically "consistent" means all or no properties are expected to be quoted, in other words quoting style can't be mixed within an object. Please note the latter situation (no quotation at all) isn't always possible as some property names require quoting.

/*eslint quote-props: ["error", "consistent"]*/

var object1 = {
    foo: "bar",
    "baz": 42,
    "qux-lorem": true
};

var object2 = {
    'foo': 'bar',
    baz: 42
};

The following patterns are not considered problems:

/*eslint quote-props: ["error", "consistent"]*/

var object1 = {
    "foo": "bar",
    "baz": 42,
    "qux-lorem": true
};

var object2 = {
    'foo': 'bar',
    'baz': 42
};

var object3 = {
    foo: 'bar',
    baz: 42
};

"consistent-as-needed"

When configured with "consistent-as-needed", the behavior is similar to "consistent" with one difference. Namely, properties' quoting should be consistent (as in "consistent") but whenever all quotes are redundant a warning is raised. In other words if at least one property name has to be quoted (like qux-lorem) then all property names must be quoted, otherwise no properties can be quoted. The following patterns are considered problems:

/*eslint quote-props: ["error", "consistent-as-needed"]*/

var object1 = {
    foo: "bar",
    "baz": 42,
    "qux-lorem": true
};

var object2 = {
    'foo': 'bar',
    'baz': 42
};

The following patterns are not considered problems:

/*eslint quote-props: ["error", "consistent-as-needed"]*/

var object1 = {
    "foo": "bar",
    "baz": 42,
    "qux-lorem": true
};

var object2 = {
    foo: 'bar',
    baz: 42
};

When the "consistent-as-needed" mode is selected, an additional keywords option can be provided. This flag indicates whether language keywords can be used unquoted as properties. By default it is set to false.

{
    "quote-props": ["error", "consistent-as-needed", { "keywords": true }]
}

When keywords is set to true, the following patterns are considered problems:

/*eslint quote-props: ["error", "consistent-as-needed", { "keywords": true }]*/

var x = {
    while: 1,
    volatile: "foo"
};

When Not To Use It

If you don't care if property names are consistently wrapped in quotes or not, and you don't target legacy ES3 environments, turn this rule off.

Further Reading

• Reserved words as property names
• Unquoted property names / object keys in JavaScript Source: http://eslint.org/docs/rules/

          })

Close

Enforce or Disallow Semicolons (semi)

(fixable) The --fix option on the [command line](../user-guide/command-line-interface#fix) automatically fixes problems reported by this rule.

JavaScript is unique amongst the C-like languages in that it doesn't require semicolons at the end of each statement. In many cases, the JavaScript engine can determine that a semicolon should be in a certain spot and will automatically add it. This feature is known as automatic semicolon insertion (ASI) and is considered one of the more controversial features of JavaScript. For example, the following lines are both valid:

var name = "ESLint"
var website = "eslint.org";

On the first line, the JavaScript engine will automatically insert a semicolon, so this is not considered a syntax error. The JavaScript engine still knows how to interpret the line and knows that the line end indicates the end of the statement.

In the debate over ASI, there are generally two schools of thought. The first is that we should treat ASI as if it didn't exist and always include semicolons manually. The rationale is that it's easier to always include semicolons than to try to remember when they are or are not required, and thus decreases the possibility of introducing an error.

However, the ASI mechanism can sometimes be tricky to people who are using semicolons. For example, consider this code:

return
{
    name: "ESLint"
};

This may look like a return statement that returns an object literal, however, the JavaScript engine will interpret this code as:

return;
{
    name: "ESLint";
}

Effectively, a semicolon is inserted after the return statement, causing the code below it (a labeled literal inside a block) to be unreachable. This rule and the [no-unreachable](no-unreachable.md) rule will protect your code from such cases.

On the other side of the argument are those who says that since semicolons are inserted automatically, they are optional and do not need to be inserted manually. However, the ASI mechanism can also be tricky to people who don't use semicolons. For example, consider this code:

var globalCounter = { }

(function () {
    var n = 0
    globalCounter.increment = function () {
        return ++n
    }
})()

In this example, a semicolon will not be inserted after the first line, causing a run-time error (because an empty object is called as if it's a function). The [no-unexpected-multiline](no-unexpected-multiline.md) rule can protect your code from such cases.

Although ASI allows for more freedom over your coding style, it can also make your code behave in an unexpected way, whether you use semicolons or not. Therefore, it is best to know when ASI takes place and when it does not, and have ESLint protect your code from these potentially unexpected cases. In short, as once described by Isaac Schlueter, a \n character always ends a statement (just like a semicolon) unless one of the following is true:

1. The statement has an unclosed paren, array literal, or object literal or ends in some other way that is not a valid way to end a statement. (For instance, ending with . or ,.)
2. The line is -- or ++ (in which case it will decrement/increment the next token.)
3. It is a for(), while(), do, if(), or else, and there is no {
4. The next line starts with [, (, +, *, /, -, ,, ., or some other binary operator that can only be found between two tokens in a single expression.

Rule Details

This rule is aimed at ensuring consistent use of semicolons. You can decide whether or not to require semicolons at the end of statements.

Options

The rule takes one or two options. The first one is a string, which could be "always" or "never". The default is "always". The second one is an object for more fine-grained configuration when the first option is "always".

You can set the option in configuration like this:

"always"

By using the default option, semicolons must be used any place where they are valid.

semi: ["error", "always"]

The following patterns are considered problems:

/*eslint semi: "error"*/

var name = "ESLint"

object.method = function() {
    // ...
}

The following patterns are not considered problems:

/*eslint semi: "error"*/

var name = "ESLint";

object.method = function() {
    // ...
};

Fine-grained control

When setting the first option as "always", an additional option can be added to omit the last semicolon in a one-line block, that is, a block in which its braces (and therefore the content of the block) are in the same line:

semi: ["error", "always", { "omitLastInOneLineBlock": true}]

The following patterns are considered problems:

/*eslint semi: ["error", "always", { "omitLastInOneLineBlock": true}] */

if (foo) {
    bar()
}

if (foo) { bar(); }

The following patterns are not considered problems:

/*eslint semi: ["error", "always", { "omitLastInOneLineBlock": true}] */

if (foo) { bar() }

if (foo) { bar(); baz() }

"never"

If you want to enforce that semicolons are never used, switch the configuration to:

semi: [2, "never"]

Then, the following patterns are considered problems:

/*eslint semi: ["error", "never"]*/

var name = "ESLint";

object.method = function() {
    // ...
};

And the following patterns are not considered problems:

/*eslint semi: ["error", "never"]*/

var name = "ESLint"

object.method = function() {
    // ...
}

Even in "never" mode, semicolons are still allowed to disambiguate statements beginning with [, (, /, +, or -:

/*eslint semi: ["error", "never"]*/

var name = "ESLint"

;(function() {
    // ...
})()

When Not To Use It

If you do not want to enforce semicolon usage (or omission) in any particular way, then you can turn this rule off.

Further Reading

• An Open Letter to JavaScript Leaders Regarding Semicolons
• JavaScript Semicolon Insertion
• Understanding Automatic Semicolon Insertion in JavaScript

Related Rules

• [no-extra-semi](no-extra-semi.md)
• [no-unexpected-multiline](no-unexpected-multiline.md)
• [semi-spacing](semi-spacing.md) Source: http://eslint.org/docs/rules/

      return Object.keys(data_.groups.group_mapping.studyMap).reduce(function(a, b) {

Close

enforce a maximum line length (max-len)

Very long lines of code in any language can be difficult to read. In order to aid in readability and maintainability many coders have developed a convention to limit lines of code to X number of characters (traditionally 80 characters).

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // very long

Rule Details

This rule enforces a maximum line length to increase code readability and maintainability.

Note: This rule calculates the length of a line via code points, not characters. That means if you use a double-byte character in your code, it will count as 2 code points instead of 1, and 2 will be used to calculate line length. This is a technical limitation of JavaScript that is made easier with ES2015, and we will look to update this when ES2015 is available in Node.js.

Options

This rule has a number or object option:

• "code" (default 80) enforces a maximum line length
• "tabWidth" (default 4) specifies the character width for tab characters
• "comments" enforces a maximum line length for comments; defaults to value of code
• "ignorePattern" ignores lines matching a regular expression; can only match a single line and need to be double escaped when written in YAML or JSON
• "ignoreComments": true ignores all trailing comments and comments on their own line
• "ignoreTrailingComments": true ignores only trailing comments
• "ignoreUrls": true ignores lines that contain a URL

code

Examples of incorrect code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" };

Examples of correct code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = {
  "bar": "This is a bar.",
  "baz": { "qux": "This is a qux" },
  "easier": "to read"
};

tabWidth

Examples of incorrect code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" } };

Examples of correct code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = {
\t  \t  \t  \t  "bar": "This is a bar.",
\t  \t  \t  \t  "baz": { "qux": "This is a qux" }
\t  \t  };

comments

Examples of incorrect code for this rule with the { "comments": 65 } option:

/*eslint max-len: ["error", { "comments": 65 }]*/

/**
 * This is a comment that violates the maximum line length we have specified
**/

ignoreComments

Examples of correct code for this rule with the { "ignoreComments": true } option:

/*eslint max-len: ["error", { "ignoreComments": true }]*/

/**
 * This is a really really really really really really really really really long comment
**/

ignoreTrailingComments

Examples of correct code for this rule with the { "ignoreTrailingComments": true } option:

/*eslint max-len: ["error", { "ignoreTrailingComments": true }]*/

var foo = 'bar'; // This is a really really really really really really really long comment

ignoreUrls

Examples of correct code for this rule with the { "ignoreUrls": true } option:

/*eslint max-len: ["error", { "ignoreUrls": true }]*/

var url = 'https://www.example.com/really/really/really/really/really/really/really/long';

ignorePattern

Examples of correct code for this rule with the { "ignorePattern": true } option:

/*eslint max-len: ["error", { "ignorePattern": "^\\s*var\\s.+=\\s*require\\s*\\(/" }]*/

var dep = require('really/really/really/really/really/really/really/really/long/module');

Related Rules

• [complexity](complexity.md)
• [max-depth](max-depth.md)
• [max-nested-callbacks](max-nested-callbacks.md)
• [max-params](max-params.md)
• [max-statements](max-statements.md) Source: http://eslint.org/docs/rules/

          QueryByGeneUtil. query (cohortIdsList ? cohortIdsList: window.cohortIdsList, this.stat(),

Close

enforce a maximum line length (max-len)

Very long lines of code in any language can be difficult to read. In order to aid in readability and maintainability many coders have developed a convention to limit lines of code to X number of characters (traditionally 80 characters).

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // very long

Rule Details

This rule enforces a maximum line length to increase code readability and maintainability.

Note: This rule calculates the length of a line via code points, not characters. That means if you use a double-byte character in your code, it will count as 2 code points instead of 1, and 2 will be used to calculate line length. This is a technical limitation of JavaScript that is made easier with ES2015, and we will look to update this when ES2015 is available in Node.js.

Options

This rule has a number or object option:

• "code" (default 80) enforces a maximum line length
• "tabWidth" (default 4) specifies the character width for tab characters
• "comments" enforces a maximum line length for comments; defaults to value of code
• "ignorePattern" ignores lines matching a regular expression; can only match a single line and need to be double escaped when written in YAML or JSON
• "ignoreComments": true ignores all trailing comments and comments on their own line
• "ignoreTrailingComments": true ignores only trailing comments
• "ignoreUrls": true ignores lines that contain a URL

code

Examples of incorrect code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" };

Examples of correct code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = {
  "bar": "This is a bar.",
  "baz": { "qux": "This is a qux" },
  "easier": "to read"
};

tabWidth

Examples of incorrect code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" } };

Examples of correct code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = {
\t  \t  \t  \t  "bar": "This is a bar.",
\t  \t  \t  \t  "baz": { "qux": "This is a qux" }
\t  \t  };

comments

Examples of incorrect code for this rule with the { "comments": 65 } option:

/*eslint max-len: ["error", { "comments": 65 }]*/

/**
 * This is a comment that violates the maximum line length we have specified
**/

ignoreComments

Examples of correct code for this rule with the { "ignoreComments": true } option:

/*eslint max-len: ["error", { "ignoreComments": true }]*/

/**
 * This is a really really really really really really really really really long comment
**/

ignoreTrailingComments

Examples of correct code for this rule with the { "ignoreTrailingComments": true } option:

/*eslint max-len: ["error", { "ignoreTrailingComments": true }]*/

var foo = 'bar'; // This is a really really really really really really really long comment

ignoreUrls

Examples of correct code for this rule with the { "ignoreUrls": true } option:

/*eslint max-len: ["error", { "ignoreUrls": true }]*/

var url = 'https://www.example.com/really/really/really/really/really/really/really/long';

ignorePattern

Examples of correct code for this rule with the { "ignorePattern": true } option:

/*eslint max-len: ["error", { "ignorePattern": "^\\s*var\\s.+=\\s*require\\s*\\(/" }]*/

var dep = require('really/really/really/really/really/really/really/really/long/module');

Related Rules

• [complexity](complexity.md)
• [max-depth](max-depth.md)
• [max-nested-callbacks](max-nested-callbacks.md)
• [max-params](max-params.md)
• [max-statements](max-statements.md) Source: http://eslint.org/docs/rules/

          QueryByGeneUtil. query (cohortIdsList ? cohortIdsList: window.cohortIdsList, this.stat(),

Close

Require Spaces Around Infix Operators (space-infix-ops)

(fixable) The --fix option on the [command line](../user-guide/command-line-interface#fix) automatically fixes problems reported by this rule.

While formatting preferences are very personal, a number of style guides require spaces around operators, such as:

var sum = 1 + 2;

The proponents of these extra spaces believe it make the code easier to read and can more easily highlight potential errors, such as:

var sum = i+++2;

While this is valid JavaScript syntax, it is hard to determine what the author intended.

Rule Details

This rule is aimed at ensuring there are spaces around infix operators.

Options

This rule accepts a single options argument with the following defaults:

"space-infix-ops": ["error", {"int32Hint": false}]

int32Hint

Set the int32Hint option to true (default is false) to allow write a|0 without space.

var foo = bar|0; // `foo` is forced to be signed 32 bit integer

The following patterns are considered problems:

/*eslint space-infix-ops: "error"*/
/*eslint-env es6*/

a+b

a+ b

a +b

a?b:c

const a={b:1};

var {a=0}=bar;

function foo(a=0) { }

The following patterns are not considered problems:

/*eslint space-infix-ops: "error"*/
/*eslint-env es6*/

a + b

a       + b

a ? b : c

const a = {b:1};

var {a = 0} = bar;

function foo(a = 0) { }

Source: http://eslint.org/docs/rules/

        $.when(self.getStudyToSampleToPatientMap(), self.getConfigs()).done(function(_studyToSampleToPatientMap, _configs) {

Close

enforce a maximum line length (max-len)

Very long lines of code in any language can be difficult to read. In order to aid in readability and maintainability many coders have developed a convention to limit lines of code to X number of characters (traditionally 80 characters).

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // very long

Rule Details

This rule enforces a maximum line length to increase code readability and maintainability.

Note: This rule calculates the length of a line via code points, not characters. That means if you use a double-byte character in your code, it will count as 2 code points instead of 1, and 2 will be used to calculate line length. This is a technical limitation of JavaScript that is made easier with ES2015, and we will look to update this when ES2015 is available in Node.js.

Options

This rule has a number or object option:

• "code" (default 80) enforces a maximum line length
• "tabWidth" (default 4) specifies the character width for tab characters
• "comments" enforces a maximum line length for comments; defaults to value of code
• "ignorePattern" ignores lines matching a regular expression; can only match a single line and need to be double escaped when written in YAML or JSON
• "ignoreComments": true ignores all trailing comments and comments on their own line
• "ignoreTrailingComments": true ignores only trailing comments
• "ignoreUrls": true ignores lines that contain a URL

code

Examples of incorrect code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" };

Examples of correct code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = {
  "bar": "This is a bar.",
  "baz": { "qux": "This is a qux" },
  "easier": "to read"
};

tabWidth

Examples of incorrect code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" } };

Examples of correct code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = {
\t  \t  \t  \t  "bar": "This is a bar.",
\t  \t  \t  \t  "baz": { "qux": "This is a qux" }
\t  \t  };

comments

Examples of incorrect code for this rule with the { "comments": 65 } option:

/*eslint max-len: ["error", { "comments": 65 }]*/

/**
 * This is a comment that violates the maximum line length we have specified
**/

ignoreComments

Examples of correct code for this rule with the { "ignoreComments": true } option:

/*eslint max-len: ["error", { "ignoreComments": true }]*/

/**
 * This is a really really really really really really really really really long comment
**/

ignoreTrailingComments

Examples of correct code for this rule with the { "ignoreTrailingComments": true } option:

/*eslint max-len: ["error", { "ignoreTrailingComments": true }]*/

var foo = 'bar'; // This is a really really really really really really really long comment

ignoreUrls

Examples of correct code for this rule with the { "ignoreUrls": true } option:

/*eslint max-len: ["error", { "ignoreUrls": true }]*/

var url = 'https://www.example.com/really/really/really/really/really/really/really/long';

ignorePattern

Examples of correct code for this rule with the { "ignorePattern": true } option:

/*eslint max-len: ["error", { "ignorePattern": "^\\s*var\\s.+=\\s*require\\s*\\(/" }]*/

var dep = require('really/really/really/really/really/really/really/really/long/module');

Related Rules

• [complexity](complexity.md)
• [max-depth](max-depth.md)
• [max-nested-callbacks](max-nested-callbacks.md)
• [max-params](max-params.md)
• [max-statements](max-statements.md) Source: http://eslint.org/docs/rules/

                _.each(caseList.cnaSampleIds, function(sampleId) {

Close

enforce a maximum depth that callbacks can be nested (max-nested-callbacks)

Many JavaScript libraries use the callback pattern to manage asynchronous operations. A program of any complexity will most likely need to manage several asynchronous operations at various levels of concurrency. A common pitfall that is easy to fall into is nesting callbacks, which makes code more difficult to read the deeper the callbacks are nested.

foo(function () {
    bar(function () {
        baz(function() {
            qux(function () {

            });
        });
    });
});

Rule Details

This rule enforces a maximum depth that callbacks can be nested to increase code clarity.

Options

This rule has a number or object option:

• "max" (default 10) enforces a maximum depth that callbacks can be nested

Deprecated: The object property maximum is deprecated; please use the object property max instead.

max

Examples of incorrect code for this rule with the { "max": 3 } option:

/*eslint max-nested-callbacks: ["error", 3]*/

foo1(function() {
    foo2(function() {
        foo3(function() {
            foo4(function() {
                // Do something
            });
        });
    });
});

Examples of correct code for this rule with the { "max": 3 } option:

/*eslint max-nested-callbacks: ["error", 3]*/

foo1(handleFoo1);

function handleFoo1() {
    foo2(handleFoo2);
}

function handleFoo2() {
    foo3(handleFoo3);
}

function handleFoo3() {
    foo4(handleFoo4);
}

function handleFoo4() {
    foo5();
}

Further Reading

• Control flow in Node.js
• Control Flow in Node
• Control Flow in Node Part II

Related Rules

• [complexity](complexity.md)
• [max-depth](max-depth.md)
• [max-len](max-len.md)
• [max-params](max-params.md)
• [max-statements](max-statements.md) Source: http://eslint.org/docs/rules/

                  iViz.priorityManager

Close

Disallow Undeclared Variables (no-undef)

This rule can help you locate potential ReferenceErrors resulting from misspellings of variable and parameter names, or accidental implicit globals (for example, from forgetting the var keyword in a for loop initializer).

Rule Details

Any reference to an undeclared variable causes a warning, unless the variable is explicitly mentioned in a /*global ...*/ comment.

Examples of incorrect code for this rule:

/*eslint no-undef: "error"*/

var a = someFunction();
b = 10;

Examples of correct code for this rule with global declaration:

/*global someFunction b:true*/
/*eslint no-undef: "error"*/

var a = someFunction();
b = 10;

The b:true syntax in /*global */ indicates that assignment to b is correct.

Examples of incorrect code for this rule with global declaration:

/*global b*/
/*eslint no-undef: "error"*/

b = 10;

By default, variables declared in /*global */ are read-only, therefore assignment is incorrect.

Options

• typeof set to true will warn for variables used inside typeof check (Default false).

typeof

Examples of correct code for the default { "typeof": false } option:

/*eslint no-undef: "error"*/

if (typeof UndefinedIdentifier === "undefined") {
    // do something ...
}

You can use this option if you want to prevent typeof check on a variable which has not been declared.

Examples of incorrect code for the { "typeof": true } option:

/*eslint no-undef: ["error", { "typeof": true }] */

if(typeof a === "string"){}

Examples of correct code for the { "typeof": true } option with global declaration:

/*global a*/
/*eslint no-undef: ["error", { "typeof": true }] */

if(typeof a === "string"){}

Environments

For convenience, ESLint provides shortcuts that pre-define global variables exposed by popular libraries and runtime environments. This rule supports these environments, as listed in Specifying Environments. A few examples are given below.

browser

Examples of correct code for this rule with browser environment:

/*eslint no-undef: "error"*/
/*eslint-env browser*/

setTimeout(function() {
    alert("Hello");
});

node

Examples of correct code for this rule with node environment:

/*eslint no-undef: "error"*/
/*eslint-env node*/

var fs = require("fs");
module.exports = function() {
    console.log(fs);
};

When Not To Use It

If explicit declaration of global variables is not to your taste.

Compatibility

This rule provides compatibility with treatment of global variables in JSHint and JSLint.

Further Reading

• '{a}' is not defined Source: http://eslint.org/docs/rules/

                case 'DFS_STATUS':

Close

enforce consistent indentation (indent)

(fixable) The --fix option on the [command line](../user-guide/command-line-interface#fix) automatically fixes problems reported by this rule.

There are several common guidelines which require specific indentation of nested blocks and statements, like:

function hello(indentSize, type) {
    if (indentSize === 4 && type !== 'tab') {
        console.log('Each next indentation will increase on 4 spaces');
    }
}

These are the most common scenarios recommended in different style guides:

• Two spaces, not longer and no tabs: Google, npm, Node.js, Idiomatic, Felix
• Tabs: jQuery
• Four spaces: Crockford

Rule Details

This rule enforces a consistent indentation style. The default style is 4 spaces.

Options

This rule has a mixed option:

For example, for 2-space indentation:

{
    "indent": ["error", 2]
}

Or for tabbed indentation:

{
    "indent": ["error", "tab"]
}

Examples of incorrect code for this rule with the default options:

/*eslint indent: "error"*/

if (a) {
  b=c;
  function foo(d) {
    e=f;
  }
}

Examples of correct code for this rule with the default options:

/*eslint indent: "error"*/

if (a) {
    b=c;
    function foo(d) {
        e=f;
    }
}

This rule has an object option:

• "SwitchCase" (default: 0) enforces indentation level for case clauses in switch statements
• "VariableDeclarator" (default: 1) enforces indentation level for var declarators; can also take an object to define separate rules for var, let and const declarations.

Level of indentation denotes the multiple of the indent specified. Example:

• Indent of 4 spaces with VariableDeclarator set to 2 will indent the multi-line variable declarations with 8 spaces.
• Indent of 2 spaces with VariableDeclarator set to 2 will indent the multi-line variable declarations with 4 spaces.
• Indent of 2 spaces with VariableDeclarator set to {"var": 2, "let": 2, "const": 3} will indent the multi-line variable declarations with 4 spaces for var and let, 6 spaces for const statements.
• Indent of tab with VariableDeclarator set to 2 will indent the multi-line variable declarations with 2 tabs.
• Indent of 2 spaces with SwitchCase set to 0 will not indent case clauses with respect to switch statements.
• Indent of 2 spaces with SwitchCase set to 2 will indent case clauses with 4 spaces with respect to switch statements.
• Indent of tabs with SwitchCase set to 2 will indent case clauses with 2 tabs with respect to switch statements.

tab

Examples of incorrect code for this rule with the "tab" option:

/*eslint indent: ["error", "tab"]*/

if (a) {
     b=c;
function foo(d) {
           e=f;
 }
}

Examples of correct code for this rule with the "tab" option:

/*eslint indent: ["error", "tab"]*/

if (a) {
/*tab*/b=c;
/*tab*/function foo(d) {
/*tab*//*tab*/e=f;
/*tab*/}
}

SwitchCase

Examples of incorrect code for this rule with the 2, { "SwitchCase": 1 } options:

/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/

switch(a){
case "a":
    break;
case "b":
    break;
}

Examples of correct code for this rule with the 2, { "SwitchCase": 1 } option:

/*eslint indent: ["error", 2, { "SwitchCase": 1 }]*/

switch(a){
  case "a":
    break;
  case "b":
    break;
}

VariableDeclarator

Examples of incorrect code for this rule with the 2, { "VariableDeclarator": 1 } options:

/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/

var a,
    b,
    c;
let a,
    b,
    c;
const a = 1,
    b = 2,
    c = 3;

Examples of correct code for this rule with the 2, { "VariableDeclarator": 1 } options:

/*eslint indent: ["error", 2, { "VariableDeclarator": 1 }]*/
/*eslint-env es6*/

var a,
  b,
  c;
let a,
  b,
  c;
const a = 1,
  b = 2,
  c = 3;

Examples of correct code for this rule with the 2, { "VariableDeclarator": 2 } options:

/*eslint indent: ["error", 2, { "VariableDeclarator": 2 }]*/
/*eslint-env es6*/

var a,
    b,
    c;
let a,
    b,
    c;
const a = 1,
    b = 2,
    c = 3;

Examples of correct code for this rule with the 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } } options:

/*eslint indent: ["error", 2, { "VariableDeclarator": { "var": 2, "let": 2, "const": 3 } }]*/
/*eslint-env es6*/

var a,
    b,
    c;
let a,
    b,
    c;
const a = 1,
      b = 2,
      c = 3;

Compatibility

• JSHint: indent
• JSCS: validateIndentation Source: http://eslint.org/docs/rules/

                _mutCntAttrMeta.attrList = ['MUTATION_COUNT', 'FRACTION_GENOME_ALTERED'];

Close

enforce a maximum line length (max-len)

Very long lines of code in any language can be difficult to read. In order to aid in readability and maintainability many coders have developed a convention to limit lines of code to X number of characters (traditionally 80 characters).

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // very long

Rule Details

This rule enforces a maximum line length to increase code readability and maintainability.

Note: This rule calculates the length of a line via code points, not characters. That means if you use a double-byte character in your code, it will count as 2 code points instead of 1, and 2 will be used to calculate line length. This is a technical limitation of JavaScript that is made easier with ES2015, and we will look to update this when ES2015 is available in Node.js.

Options

This rule has a number or object option:

• "code" (default 80) enforces a maximum line length
• "tabWidth" (default 4) specifies the character width for tab characters
• "comments" enforces a maximum line length for comments; defaults to value of code
• "ignorePattern" ignores lines matching a regular expression; can only match a single line and need to be double escaped when written in YAML or JSON
• "ignoreComments": true ignores all trailing comments and comments on their own line
• "ignoreTrailingComments": true ignores only trailing comments
• "ignoreUrls": true ignores lines that contain a URL

code

Examples of incorrect code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" };

Examples of correct code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = {
  "bar": "This is a bar.",
  "baz": { "qux": "This is a qux" },
  "easier": "to read"
};

tabWidth

Examples of incorrect code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" } };

Examples of correct code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = {
\t  \t  \t  \t  "bar": "This is a bar.",
\t  \t  \t  \t  "baz": { "qux": "This is a qux" }
\t  \t  };

comments

Examples of incorrect code for this rule with the { "comments": 65 } option:

/*eslint max-len: ["error", { "comments": 65 }]*/

/**
 * This is a comment that violates the maximum line length we have specified
**/

ignoreComments

Examples of correct code for this rule with the { "ignoreComments": true } option:

/*eslint max-len: ["error", { "ignoreComments": true }]*/

/**
 * This is a really really really really really really really really really long comment
**/

ignoreTrailingComments

Examples of correct code for this rule with the { "ignoreTrailingComments": true } option:

/*eslint max-len: ["error", { "ignoreTrailingComments": true }]*/

var foo = 'bar'; // This is a really really really really really really really long comment

ignoreUrls

Examples of correct code for this rule with the { "ignoreUrls": true } option:

/*eslint max-len: ["error", { "ignoreUrls": true }]*/

var url = 'https://www.example.com/really/really/really/really/really/really/really/long';

ignorePattern

Examples of correct code for this rule with the { "ignorePattern": true } option:

/*eslint max-len: ["error", { "ignorePattern": "^\\s*var\\s.+=\\s*require\\s*\\(/" }]*/

var dep = require('really/really/really/really/really/really/really/really/long/module');

Related Rules

• [complexity](complexity.md)
• [max-depth](max-depth.md)
• [max-nested-callbacks](max-nested-callbacks.md)
• [max-params](max-params.md)
• [max-statements](max-statements.md) Source: http://eslint.org/docs/rules/

      var fetch_promises = [];

Close

Disallow Unused Variables (no-unused-vars)

Variables that are declared and not used anywhere in the code are most likely an error due to incomplete refactoring. Such variables take up space in the code and can lead to confusion by readers.

Rule Details

This rule is aimed at eliminating unused variables, functions, and parameters of functions.

A variable is considered to be used if any of the following are true:

• It represents a function that is called (doSomething())
• It is read (var y = x)
• It is passed into a function as an argument (doSomething(x))

A variable is not considered to be used if it is only ever assigned to (var x = 5) or declared.

Examples of incorrect code for this rule:

/*eslint no-unused-vars: "error"*/
/*global some_unused_var*/

//It checks variables you have defined as global
some_unused_var = 42;

var x;

var y = 10;
y = 5;

// By default, unused arguments cause warnings.
(function(foo) {
    return 5;
})();

// Unused recursive functions also cause warnings.
function fact(n) {
    if (n < 2) return 1;
    return n * fact(n - 1);
}

Examples of correct code for this rule:

/*eslint no-unused-vars: "error"*/

var x = 10;
alert(x);

// foo is considered used here
myFunc(function foo() {
    // ...
}.bind(this));

(function(foo) {
    return foo;
})();

exported

In environments outside of CommonJS or ECMAScript modules, you may use var to create a global variable that may be used by other scripts. You can use the /* exported variableName */ comment block to indicate that this variable is being exported and therefore should not be considered unused.

Note that /* exported */ has no effect for any of the following:

• when the environment is node or commonjs
• when parserOptions.sourceType is module
• when ecmaFeatures.globalReturn is true

Options

This rule takes one argument which can be a string or an object. The string settings are the same as those of the vars property (explained below).

By default this rule is enabled with all option for variables and after-used for arguments.

{
    "rules": {
        "no-unused-vars": ["error", { "vars": "all", "args": "after-used" }]
    }
}

vars

The vars option has two settings:

• all checks all variables for usage, including those in the global scope. This is the default setting.
• local checks only that locally-declared variables are used but will allow global variables to be unused.

vars: local

Examples of correct code for the { "vars": "local" } option:

/*eslint no-unused-vars: ["error", { "vars": "local" }]*/
/*global some_unused_var */

some_unused_var = 42;

varsIgnorePattern

The varsIgnorePattern option specifies exceptions not to check for usage: variables whose names match a regexp pattern. For example, variables whose names contain ignored or Ignored.

Examples of correct code for the { "varsIgnorePattern": "[iI]gnored" } option:

/*eslint no-unused-vars: ["error", { "varsIgnorePattern": "[iI]gnored" }]*/

var firstVarIgnored = 1;
var secondVar = 2;
console.log(secondVar);

args

The args option has three settings:

• after-used - only the last argument must be used. This allows you, for instance, to have two named parameters to a function and as long as you use the second argument, ESLint will not warn you about the first. This is the default setting.
• all - all named arguments must be used.
• none - do not check arguments.

args: after-used

Examples of incorrect code for the default { "args": "after-used" } option:

/*eslint no-unused-vars: ["error", { "args": "after-used" }]*/

// 1 error
// "baz" is defined but never used
(function(foo, bar, baz) {
    return bar;
})();

Examples of correct code for the default { "args": "after-used" } option:

/*eslint no-unused-vars: ["error", {"args": "after-used"}]*/

(function(foo, bar, baz) {
    return baz;
})();

args: all

Examples of incorrect code for the { "args": "all" } option:

/*eslint no-unused-vars: ["error", { "args": "all" }]*/

// 2 errors
// "foo" is defined but never used
// "baz" is defined but never used
(function(foo, bar, baz) {
    return bar;
})();

args: none

Examples of correct code for the { "args": "none" } option:

/*eslint no-unused-vars: ["error", { "args": "none" }]*/

(function(foo, bar, baz) {
    return bar;
})();

argsIgnorePattern

The argsIgnorePattern option specifies exceptions not to check for usage: arguments whose names match a regexp pattern. For example, variables whose names begin with an underscore.

Examples of correct code for the { "argsIgnorePattern": "^_" } option:

/*eslint no-unused-vars: ["error", { "argsIgnorePattern": "^_" }]*/

function foo(x, _y) {
    return x + 1;
}
foo();

caughtErrors

The caughtErrors option is used for catch block arguments validation.

It has two settings:

• none - do not check error objects. This is the default setting.
• all - all named arguments must be used.

caughtErrors: none

Not specifying this rule is equivalent of assigning it to none.

Examples of correct code for the { "caughtErrors": "none" } option:

/*eslint no-unused-vars: ["error", { "caughtErrors": "none" }]*/

try {
    //...
} catch (err) {
    console.error("errors");
}

caughtErrors: all

Examples of incorrect code for the { "caughtErrors": "all" } option:

/*eslint no-unused-vars: ["error", { "caughtErrors": "all" }]*/

// 1 error
// "err" is defined but never used
try {
    //...
} catch (err) {
    console.error("errors");
}

caughtErrorsIgnorePattern

The caughtErrorsIgnorePattern option specifies exceptions not to check for usage: catch arguments whose names match a regexp pattern. For example, variables whose names begin with a string 'ignore'.

Examples of correct code for the { "caughtErrorsIgnorePattern": "^ignore" } option:

/*eslint no-unused-vars: ["error", { "caughtErrorsIgnorePattern": "^ignore" }]*/

try {
    //...
} catch (ignoreErr) {
    console.error("errors");
}

When Not To Use It

If you don't want to be notified about unused variables or function arguments, you can safely turn this rule off. Source: http://eslint.org/docs/rules/

              }

Close

Enforce or Disallow Semicolons (semi)

(fixable) The --fix option on the [command line](../user-guide/command-line-interface#fix) automatically fixes problems reported by this rule.

JavaScript is unique amongst the C-like languages in that it doesn't require semicolons at the end of each statement. In many cases, the JavaScript engine can determine that a semicolon should be in a certain spot and will automatically add it. This feature is known as automatic semicolon insertion (ASI) and is considered one of the more controversial features of JavaScript. For example, the following lines are both valid:

var name = "ESLint"
var website = "eslint.org";

On the first line, the JavaScript engine will automatically insert a semicolon, so this is not considered a syntax error. The JavaScript engine still knows how to interpret the line and knows that the line end indicates the end of the statement.

In the debate over ASI, there are generally two schools of thought. The first is that we should treat ASI as if it didn't exist and always include semicolons manually. The rationale is that it's easier to always include semicolons than to try to remember when they are or are not required, and thus decreases the possibility of introducing an error.

However, the ASI mechanism can sometimes be tricky to people who are using semicolons. For example, consider this code:

return
{
    name: "ESLint"
};

This may look like a return statement that returns an object literal, however, the JavaScript engine will interpret this code as:

return;
{
    name: "ESLint";
}

Effectively, a semicolon is inserted after the return statement, causing the code below it (a labeled literal inside a block) to be unreachable. This rule and the [no-unreachable](no-unreachable.md) rule will protect your code from such cases.

On the other side of the argument are those who says that since semicolons are inserted automatically, they are optional and do not need to be inserted manually. However, the ASI mechanism can also be tricky to people who don't use semicolons. For example, consider this code:

var globalCounter = { }

(function () {
    var n = 0
    globalCounter.increment = function () {
        return ++n
    }
})()

In this example, a semicolon will not be inserted after the first line, causing a run-time error (because an empty object is called as if it's a function). The [no-unexpected-multiline](no-unexpected-multiline.md) rule can protect your code from such cases.

Although ASI allows for more freedom over your coding style, it can also make your code behave in an unexpected way, whether you use semicolons or not. Therefore, it is best to know when ASI takes place and when it does not, and have ESLint protect your code from these potentially unexpected cases. In short, as once described by Isaac Schlueter, a \n character always ends a statement (just like a semicolon) unless one of the following is true:

1. The statement has an unclosed paren, array literal, or object literal or ends in some other way that is not a valid way to end a statement. (For instance, ending with . or ,.)
2. The line is -- or ++ (in which case it will decrement/increment the next token.)
3. It is a for(), while(), do, if(), or else, and there is no {
4. The next line starts with [, (, +, *, /, -, ,, ., or some other binary operator that can only be found between two tokens in a single expression.

Rule Details

This rule is aimed at ensuring consistent use of semicolons. You can decide whether or not to require semicolons at the end of statements.

Options

The rule takes one or two options. The first one is a string, which could be "always" or "never". The default is "always". The second one is an object for more fine-grained configuration when the first option is "always".

You can set the option in configuration like this:

"always"

By using the default option, semicolons must be used any place where they are valid.

semi: ["error", "always"]

The following patterns are considered problems:

/*eslint semi: "error"*/

var name = "ESLint"

object.method = function() {
    // ...
}

The following patterns are not considered problems:

/*eslint semi: "error"*/

var name = "ESLint";

object.method = function() {
    // ...
};

Fine-grained control

When setting the first option as "always", an additional option can be added to omit the last semicolon in a one-line block, that is, a block in which its braces (and therefore the content of the block) are in the same line:

semi: ["error", "always", { "omitLastInOneLineBlock": true}]

The following patterns are considered problems:

/*eslint semi: ["error", "always", { "omitLastInOneLineBlock": true}] */

if (foo) {
    bar()
}

if (foo) { bar(); }

The following patterns are not considered problems:

/*eslint semi: ["error", "always", { "omitLastInOneLineBlock": true}] */

if (foo) { bar() }

if (foo) { bar(); baz() }

"never"

If you want to enforce that semicolons are never used, switch the configuration to:

semi: [2, "never"]

Then, the following patterns are considered problems:

/*eslint semi: ["error", "never"]*/

var name = "ESLint";

object.method = function() {
    // ...
};

And the following patterns are not considered problems:

/*eslint semi: ["error", "never"]*/

var name = "ESLint"

object.method = function() {
    // ...
}

Even in "never" mode, semicolons are still allowed to disambiguate statements beginning with [, (, /, +, or -:

/*eslint semi: ["error", "never"]*/

var name = "ESLint"

;(function() {
    // ...
})()

When Not To Use It

If you do not want to enforce semicolon usage (or omission) in any particular way, then you can turn this rule off.

Further Reading

• An Open Letter to JavaScript Leaders Regarding Semicolons
• JavaScript Semicolon Insertion
• Understanding Automatic Semicolon Insertion in JavaScript

Related Rules

• [no-extra-semi](no-extra-semi.md)
• [no-unexpected-multiline](no-unexpected-multiline.md)
• [semi-spacing](semi-spacing.md) Source: http://eslint.org/docs/rules/

            contentType: "application/json; charset=utf-8",

Close

Enforce Quote Style (quotes)

(fixable) The --fix option on the [command line](../user-guide/command-line-interface#fix) automatically fixes problems reported by this rule.

JavaScript allows you to define strings in one of three ways: double quotes, single quotes, and backticks (as of ECMAScript 6). For example:

/*eslint-env es6*/

var double = "double";
var single = 'single';
var backtick = `backtick`;    // ES6 only

Each of these lines creates a string and, in some cases, can be used interchangeably. The choice of how to define strings in a codebase is a stylistic one outside of template literals (which allow embedded of expressions to be interpreted).

Many codebases require strings to be defined in a consistent manner.

Rule Details

This rule is aimed at ensuring consistency of string quotes and as such will report a problem when an inconsistent style is found.

The rule configuration takes up to two options:

1. The first option is "double", "single" or "backtick" for double-quotes, single-quotes or backticks respectively. The default is "double".
2. The second option takes two options:
   1. "avoidEscape": When using "avoidEscape", this rule will not report a problem when a string is using single-quotes or double-quotes so long as the string contains a quote that would have to be escaped otherwise. For example, if you specify "double" and "avoidEscape", the string 'He said, "hi!"' is not considered a problem because using double quotes for that string would require escaping the double quotes inside of the string. This option is off by default.
   2. "allowTemplateLiterals": when using "allowTemplateLiterals", this rule will not report a problem when a string is using backticks and option one is either "double" or "single".

When using "single" or "double", template literals that don't contain a substitution, don't contain a line break and aren't tagged templates, are flagged as problems, even with the "avoidEscape" option. However they are not problems when "allowTemplateLiterals" is used.

Configuration looks like this:

[2, "single", {"avoidEscape": true, "allowTemplateLiterals": true}]

Deprecation notice: The avoid-escape option is a deprecated syntax and you should use the object form instead.

The following patterns are considered problems:

/*eslint quotes: ["error", "double"]*/

var single = 'single';
var unescaped = 'a string containing "double" quotes';

/*eslint quotes: ["error", "single"]*/

var double = "double";
var unescaped = "a string containing 'single' quotes";

/*eslint quotes: ["error", "double", {"avoidEscape": true}]*/

var single = 'single';
var single = `single`;

/*eslint quotes: ["error", "single", {"avoidEscape": true}]*/

var double = "double";
var double = `double`;

/*eslint quotes: ["error", "backtick"]*/

var single = 'single';
var double = "double";
var unescaped = 'a string containing `backticks`';

/*eslint quotes: ["error", "backtick", {"avoidEscape": true}]*/

var single = 'single';
var double = "double";

The following patterns are not considered problems:

/*eslint quotes: ["error", "double"]*/
/*eslint-env es6*/

var double = "double";
var backtick = `back\ntick`;  // backticks are allowed due to newline
var backtick = tag`backtick`; // backticks are allowed due to tag

/*eslint quotes: ["error", "single"]*/
/*eslint-env es6*/

var single = 'single';
var backtick = `back${x}tick`; // backticks are allowed due to substitution

/*eslint quotes: ["error", "double", {"avoidEscape": true}]*/

var single = 'a string containing "double" quotes';

/*eslint quotes: ["error", "single", {"avoidEscape": true}]*/

var double = "a string containing 'single' quotes";

/*eslint quotes: ["error", "double", {"allowTemplateLiterals": true}]*/

var single = 'single';
var single = `single`;

/*eslint quotes: ["error", "single", {"allowTemplateLiterals": true}]*/

var double = "double";
var double = `double`;

/*eslint quotes: ["error", "backtick"]*/
/*eslint-env es6*/

var backtick = `backtick`;

/*eslint quotes: ["error", "backtick", {"avoidEscape": true}]*/

var double = "a string containing `backtick` quotes"

When Not To Use It

If you do not need consistency in your string styles, you can safely disable this rule. Source: http://eslint.org/docs/rules/

          $.get(window.cbioURL + 'api/molecular-profiles?projection=SUMMARY&pageSize=100000&pageNumber=0&sortBy=molecularProfileId&direction=ASC')

Close

enforce a maximum line length (max-len)

Very long lines of code in any language can be difficult to read. In order to aid in readability and maintainability many coders have developed a convention to limit lines of code to X number of characters (traditionally 80 characters).

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // very long

Rule Details

This rule enforces a maximum line length to increase code readability and maintainability.

Note: This rule calculates the length of a line via code points, not characters. That means if you use a double-byte character in your code, it will count as 2 code points instead of 1, and 2 will be used to calculate line length. This is a technical limitation of JavaScript that is made easier with ES2015, and we will look to update this when ES2015 is available in Node.js.

Options

This rule has a number or object option:

• "code" (default 80) enforces a maximum line length
• "tabWidth" (default 4) specifies the character width for tab characters
• "comments" enforces a maximum line length for comments; defaults to value of code
• "ignorePattern" ignores lines matching a regular expression; can only match a single line and need to be double escaped when written in YAML or JSON
• "ignoreComments": true ignores all trailing comments and comments on their own line
• "ignoreTrailingComments": true ignores only trailing comments
• "ignoreUrls": true ignores lines that contain a URL

code

Examples of incorrect code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" };

Examples of correct code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = {
  "bar": "This is a bar.",
  "baz": { "qux": "This is a qux" },
  "easier": "to read"
};

tabWidth

Examples of incorrect code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" } };

Examples of correct code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = {
\t  \t  \t  \t  "bar": "This is a bar.",
\t  \t  \t  \t  "baz": { "qux": "This is a qux" }
\t  \t  };

comments

Examples of incorrect code for this rule with the { "comments": 65 } option:

/*eslint max-len: ["error", { "comments": 65 }]*/

/**
 * This is a comment that violates the maximum line length we have specified
**/

ignoreComments

Examples of correct code for this rule with the { "ignoreComments": true } option:

/*eslint max-len: ["error", { "ignoreComments": true }]*/

/**
 * This is a really really really really really really really really really long comment
**/

ignoreTrailingComments

Examples of correct code for this rule with the { "ignoreTrailingComments": true } option:

/*eslint max-len: ["error", { "ignoreTrailingComments": true }]*/

var foo = 'bar'; // This is a really really really really really really really long comment

ignoreUrls

Examples of correct code for this rule with the { "ignoreUrls": true } option:

/*eslint max-len: ["error", { "ignoreUrls": true }]*/

var url = 'https://www.example.com/really/really/really/really/really/really/really/long';

ignorePattern

Examples of correct code for this rule with the { "ignorePattern": true } option:

/*eslint max-len: ["error", { "ignorePattern": "^\\s*var\\s.+=\\s*require\\s*\\(/" }]*/

var dep = require('really/really/really/really/really/really/really/really/long/module');

Related Rules

• [complexity](complexity.md)
• [max-depth](max-depth.md)
• [max-nested-callbacks](max-nested-callbacks.md)
• [max-params](max-params.md)
• [max-statements](max-statements.md) Source: http://eslint.org/docs/rules/

                self.data.sampleLists[list.studyId] = self.data.sampleLists[list.studyId] || {};

Close

enforce a maximum line length (max-len)

Very long lines of code in any language can be difficult to read. In order to aid in readability and maintainability many coders have developed a convention to limit lines of code to X number of characters (traditionally 80 characters).

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // very long

Rule Details

This rule enforces a maximum line length to increase code readability and maintainability.

Note: This rule calculates the length of a line via code points, not characters. That means if you use a double-byte character in your code, it will count as 2 code points instead of 1, and 2 will be used to calculate line length. This is a technical limitation of JavaScript that is made easier with ES2015, and we will look to update this when ES2015 is available in Node.js.

Options

This rule has a number or object option:

• "code" (default 80) enforces a maximum line length
• "tabWidth" (default 4) specifies the character width for tab characters
• "comments" enforces a maximum line length for comments; defaults to value of code
• "ignorePattern" ignores lines matching a regular expression; can only match a single line and need to be double escaped when written in YAML or JSON
• "ignoreComments": true ignores all trailing comments and comments on their own line
• "ignoreTrailingComments": true ignores only trailing comments
• "ignoreUrls": true ignores lines that contain a URL

code

Examples of incorrect code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" };

Examples of correct code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = {
  "bar": "This is a bar.",
  "baz": { "qux": "This is a qux" },
  "easier": "to read"
};

tabWidth

Examples of incorrect code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" } };

Examples of correct code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = {
\t  \t  \t  \t  "bar": "This is a bar.",
\t  \t  \t  \t  "baz": { "qux": "This is a qux" }
\t  \t  };

comments

Examples of incorrect code for this rule with the { "comments": 65 } option:

/*eslint max-len: ["error", { "comments": 65 }]*/

/**
 * This is a comment that violates the maximum line length we have specified
**/

ignoreComments

Examples of correct code for this rule with the { "ignoreComments": true } option:

/*eslint max-len: ["error", { "ignoreComments": true }]*/

/**
 * This is a really really really really really really really really really long comment
**/

ignoreTrailingComments

Examples of correct code for this rule with the { "ignoreTrailingComments": true } option:

/*eslint max-len: ["error", { "ignoreTrailingComments": true }]*/

var foo = 'bar'; // This is a really really really really really really really long comment

ignoreUrls

Examples of correct code for this rule with the { "ignoreUrls": true } option:

/*eslint max-len: ["error", { "ignoreUrls": true }]*/

var url = 'https://www.example.com/really/really/really/really/really/really/really/long';

ignorePattern

Examples of correct code for this rule with the { "ignorePattern": true } option:

/*eslint max-len: ["error", { "ignorePattern": "^\\s*var\\s.+=\\s*require\\s*\\(/" }]*/

var dep = require('really/really/really/really/really/really/really/really/long/module');

Related Rules

• [complexity](complexity.md)
• [max-depth](max-depth.md)
• [max-nested-callbacks](max-nested-callbacks.md)
• [max-params](max-params.md)
• [max-statements](max-statements.md) Source: http://eslint.org/docs/rules/

                self.data.sampleLists[list.studyId][list.sampleListId] = list.sampleIds.sort();

Close

enforce a maximum line length (max-len)

Very long lines of code in any language can be difficult to read. In order to aid in readability and maintainability many coders have developed a convention to limit lines of code to X number of characters (traditionally 80 characters).

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // very long

Rule Details

This rule enforces a maximum line length to increase code readability and maintainability.

Note: This rule calculates the length of a line via code points, not characters. That means if you use a double-byte character in your code, it will count as 2 code points instead of 1, and 2 will be used to calculate line length. This is a technical limitation of JavaScript that is made easier with ES2015, and we will look to update this when ES2015 is available in Node.js.

Options

This rule has a number or object option:

• "code" (default 80) enforces a maximum line length
• "tabWidth" (default 4) specifies the character width for tab characters
• "comments" enforces a maximum line length for comments; defaults to value of code
• "ignorePattern" ignores lines matching a regular expression; can only match a single line and need to be double escaped when written in YAML or JSON
• "ignoreComments": true ignores all trailing comments and comments on their own line
• "ignoreTrailingComments": true ignores only trailing comments
• "ignoreUrls": true ignores lines that contain a URL

code

Examples of incorrect code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" };

Examples of correct code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = {
  "bar": "This is a bar.",
  "baz": { "qux": "This is a qux" },
  "easier": "to read"
};

tabWidth

Examples of incorrect code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" } };

Examples of correct code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = {
\t  \t  \t  \t  "bar": "This is a bar.",
\t  \t  \t  \t  "baz": { "qux": "This is a qux" }
\t  \t  };

comments

Examples of incorrect code for this rule with the { "comments": 65 } option:

/*eslint max-len: ["error", { "comments": 65 }]*/

/**
 * This is a comment that violates the maximum line length we have specified
**/

ignoreComments

Examples of correct code for this rule with the { "ignoreComments": true } option:

/*eslint max-len: ["error", { "ignoreComments": true }]*/

/**
 * This is a really really really really really really really really really long comment
**/

ignoreTrailingComments

Examples of correct code for this rule with the { "ignoreTrailingComments": true } option:

/*eslint max-len: ["error", { "ignoreTrailingComments": true }]*/

var foo = 'bar'; // This is a really really really really really really really long comment

ignoreUrls

Examples of correct code for this rule with the { "ignoreUrls": true } option:

/*eslint max-len: ["error", { "ignoreUrls": true }]*/

var url = 'https://www.example.com/really/really/really/really/really/really/really/long';

ignorePattern

Examples of correct code for this rule with the { "ignorePattern": true } option:

/*eslint max-len: ["error", { "ignorePattern": "^\\s*var\\s.+=\\s*require\\s*\\(/" }]*/

var dep = require('really/really/really/really/really/really/really/really/long/module');

Related Rules

• [complexity](complexity.md)
• [max-depth](max-depth.md)
• [max-nested-callbacks](max-nested-callbacks.md)
• [max-params](max-params.md)
• [max-statements](max-statements.md) Source: http://eslint.org/docs/rules/

                sample_uid_to_patient_uid[_studyId] = sample_uid_to_patient_uid[_studyId] || {};

Close

enforce a maximum line length (max-len)

Very long lines of code in any language can be difficult to read. In order to aid in readability and maintainability many coders have developed a convention to limit lines of code to X number of characters (traditionally 80 characters).

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // very long

Rule Details

This rule enforces a maximum line length to increase code readability and maintainability.

Note: This rule calculates the length of a line via code points, not characters. That means if you use a double-byte character in your code, it will count as 2 code points instead of 1, and 2 will be used to calculate line length. This is a technical limitation of JavaScript that is made easier with ES2015, and we will look to update this when ES2015 is available in Node.js.

Options

This rule has a number or object option:

• "code" (default 80) enforces a maximum line length
• "tabWidth" (default 4) specifies the character width for tab characters
• "comments" enforces a maximum line length for comments; defaults to value of code
• "ignorePattern" ignores lines matching a regular expression; can only match a single line and need to be double escaped when written in YAML or JSON
• "ignoreComments": true ignores all trailing comments and comments on their own line
• "ignoreTrailingComments": true ignores only trailing comments
• "ignoreUrls": true ignores lines that contain a URL

code

Examples of incorrect code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" };

Examples of correct code for this rule with the default { "code": 80 } option:

/*eslint max-len: ["error", 80]*/

var foo = {
  "bar": "This is a bar.",
  "baz": { "qux": "This is a qux" },
  "easier": "to read"
};

tabWidth

Examples of incorrect code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" } };

Examples of correct code for this rule with the default { "tabWidth": 4 } option:

/*eslint max-len: ["error", 80, 4]*/

\t  \t  var foo = {
\t  \t  \t  \t  "bar": "This is a bar.",
\t  \t  \t  \t  "baz": { "qux": "This is a qux" }
\t  \t  };

comments

Examples of incorrect code for this rule with the { "comments": 65 } option:

/*eslint max-len: ["error", { "comments": 65 }]*/

/**
 * This is a comment that violates the maximum line length we have specified
**/

ignoreComments

Examples of correct code for this rule with the { "ignoreComments": true } option:

/*eslint max-len: ["error", { "ignoreComments": true }]*/

/**
 * This is a really really really really really really really really really long comment
**/

ignoreTrailingComments

Examples of correct code for this rule with the { "ignoreTrailingComments": true } option:

/*eslint max-len: ["error", { "ignoreTrailingComments": true }]*/

var foo = 'bar'; // This is a really really really really really really really long comment

ignoreUrls

Examples of correct code for this rule with the { "ignoreUrls": true } option:

/*eslint max-len: ["error", { "ignoreUrls": true }]*/

var url = 'https://www.example.com/really/really/really/really/really/really/really/long';

ignorePattern

Examples of correct code for this rule with the { "ignorePattern": true } option:

/*eslint max-len: ["error", { "ignorePattern": "^\\s*var\\s.+=\\s*require\\s*\\(/" }]*/

var dep = require('really/really/really/really/really/really/really/really/long/module');

Related Rules

• [complexity](complexity.md)
• [max-depth](max-depth.md)
• [max-nested-callbacks](max-nested-callbacks.md)
• [max-params](max-params.md)
• [max-statements](max-statements.md) Source: http://eslint.org/docs/rules/