huridocs/uwazi

For more information visit Source: http://eslint.org/docs/rules/

title: no-return-assign

rule_type: suggestion

One of the interesting, and sometimes confusing, aspects of JavaScript is that assignment can happen at almost any point. Because of this, an errant equals sign can end up causing assignment when the true intent was to do a comparison. This is especially true when using a return statement. For example:

function doSomething() {
    return foo = bar + 2;
}

It is difficult to tell the intent of the return statement here. It's possible that the function is meant to return the result of bar + 2, but then why is it assigning to foo? It's also possible that the intent was to use a comparison operator such as == and that this code is an error.

Because of this ambiguity, it's considered a best practice to not use assignment in return statements.

Rule Details

This rule aims to eliminate assignments from return statements. As such, it will warn whenever an assignment is found as part of return.

Options

The rule takes one option, a string, which must contain one of the following values:

• except-parens (default): Disallow assignments unless they are enclosed in parentheses.
• always: Disallow all assignments.

except-parens

This is the default option. It disallows assignments unless they are enclosed in parentheses.

Examples of incorrect code for the default "except-parens" option:

::: incorrect

/*eslint no-return-assign: "error"*/

function doSomething() {
    return foo = bar + 2;
}

function doSomething() {
    return foo += 2;
}

const foo = (a, b) => a = b

const bar = (a, b, c) => (a = b, c == b)

function doSomething() {
    return foo = bar && foo > 0;
}

:::

Examples of correct code for the default "except-parens" option:

::: correct

/*eslint no-return-assign: "error"*/

function doSomething() {
    return foo == bar + 2;
}

function doSomething() {
    return foo === bar + 2;
}

function doSomething() {
    return (foo = bar + 2);
}

const foo = (a, b) => (a = b)

const bar = (a, b, c) => ((a = b), c == b)

function doSomething() {
    return (foo = bar) && foo > 0;
}

:::

always

This option disallows all assignments in return statements. All assignments are treated as problems.

Examples of incorrect code for the "always" option:

::: incorrect

/*eslint no-return-assign: ["error", "always"]*/

function doSomething() {
    return foo = bar + 2;
}

function doSomething() {
    return foo += 2;
}

function doSomething() {
    return (foo = bar + 2);
}

:::

Examples of correct code for the "always" option:

::: correct

/*eslint no-return-assign: ["error", "always"]*/

function doSomething() {
    return foo == bar + 2;
}

function doSomething() {
    return foo === bar + 2;
}

:::

When Not To Use It

If you want to allow the use of assignment operators in a return statement, then you can safely disable this rule. Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

title: no-console ruletype: suggestion relatedrules: - no-alert

- no-debugger

In JavaScript that is designed to be executed in the browser, it's considered a best practice to avoid using methods on console. Such messages are considered to be for debugging purposes and therefore not suitable to ship to the client. In general, calls using console should be stripped before being pushed to production.

console.log("Made it here.");
console.error("That shouldn't have happened.");

Rule Details

This rule disallows calls or assignments to methods of the console object.

Examples of incorrect code for this rule:

::: incorrect

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

console.log("Log a debug level message.");
console.warn("Log a warn level message.");
console.error("Log an error level message.");
console.log = foo();

:::

Examples of correct code for this rule:

::: correct

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

// custom console
Console.log("Hello world!");

:::

Options

This rule has an object option for exceptions:

• "allow" has an array of strings which are allowed methods of the console object

Examples of additional correct code for this rule with a sample { "allow": ["warn", "error"] } option:

::: correct

/* eslint no-console: ["error", { allow: ["warn", "error"] }] */

console.warn("Log a warn level message.");
console.error("Log an error level message.");

:::

When Not To Use It

If you're using Node.js, however, console is used to output information to the user and so is not strictly used for debugging purposes. If you are developing for Node.js then you most likely do not want this rule enabled.

Another case where you might not use this rule is if you want to enforce console calls and not console overwrites. For example:

/* eslint no-console: ["error", { allow: ["warn"] }] */
console.error = function (message) {
  throw new Error(message);
};

With the no-console rule in the above example, ESLint will report an error. For the above example, you can disable the rule:

// eslint-disable-next-line no-console
console.error = function (message) {
  throw new Error(message);
};

// or

console.error = function (message) {  // eslint-disable-line no-console
  throw new Error(message);
};

However, you might not want to manually add eslint-disable-next-line or eslint-disable-line. You can achieve the effect of only receiving errors for console calls with the no-restricted-syntax rule:

{
    "rules": {
        "no-console": "off",
        "no-restricted-syntax": [
            "error",
            {
                "selector": "CallExpression[callee.object.name='console'][callee.property.name!=/^(log|warn|error|info|trace)$/]",
                "message": "Unexpected property on console object was called"
            }
        ]
    }
}

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

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/