huridocs/uwazi

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-param-reassign ruletype: suggestion furtherreading:

- https://spin.atomicobject.com/2011/04/10/javascript-don-t-reassign-your-function-arguments/

Assignment to variables declared as function parameters can be misleading and lead to confusing behavior, as modifying function parameters will also mutate the arguments object when not in strict mode (see When Not To Use It below). Often, assignment to function parameters is unintended and indicative of a mistake or programmer error.

This rule can be also configured to fail when function parameters are modified. Side effects on parameters can cause counter-intuitive execution flow and make errors difficult to track down.

Rule Details

This rule aims to prevent unintended behavior caused by modification or reassignment of function parameters.

Examples of incorrect code for this rule:

::: incorrect

/*eslint no-param-reassign: "error"*/

function foo(bar) {
    bar = 13;
}

function foo(bar) {
    bar++;
}

function foo(bar) {
    for (bar in baz) {}
}

function foo(bar) {
    for (bar of baz) {}
}

:::

Examples of correct code for this rule:

::: correct

/*eslint no-param-reassign: "error"*/

function foo(bar) {
    var baz = bar;
}

:::

Options

This rule takes one option, an object, with a boolean property "props", and arrays "ignorePropertyModificationsFor" and "ignorePropertyModificationsForRegex". "props" is false by default. If "props" is set to true, this rule warns against the modification of parameter properties unless they're included in "ignorePropertyModificationsFor" or "ignorePropertyModificationsForRegex", which is an empty array by default.

props

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

::: correct

/*eslint no-param-reassign: ["error", { "props": false }]*/

function foo(bar) {
    bar.prop = "value";
}

function foo(bar) {
    delete bar.aaa;
}

function foo(bar) {
    bar.aaa++;
}

function foo(bar) {
    for (bar.aaa in baz) {}
}

function foo(bar) {
    for (bar.aaa of baz) {}
}

:::

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

::: incorrect

/*eslint no-param-reassign: ["error", { "props": true }]*/

function foo(bar) {
    bar.prop = "value";
}

function foo(bar) {
    delete bar.aaa;
}

function foo(bar) {
    bar.aaa++;
}

function foo(bar) {
    for (bar.aaa in baz) {}
}

function foo(bar) {
    for (bar.aaa of baz) {}
}

:::

Examples of correct code for the { "props": true } option with "ignorePropertyModificationsFor" set:

::: correct

/*eslint no-param-reassign: ["error", { "props": true, "ignorePropertyModificationsFor": ["bar"] }]*/

function foo(bar) {
    bar.prop = "value";
}

function foo(bar) {
    delete bar.aaa;
}

function foo(bar) {
    bar.aaa++;
}

function foo(bar) {
    for (bar.aaa in baz) {}
}

function foo(bar) {
    for (bar.aaa of baz) {}
}

:::

Examples of correct code for the { "props": true } option with "ignorePropertyModificationsForRegex" set:

::: correct

/*eslint no-param-reassign: ["error", { "props": true, "ignorePropertyModificationsForRegex": ["^bar"] }]*/

function foo(barVar) {
    barVar.prop = "value";
}

function foo(barrito) {
    delete barrito.aaa;
}

function foo(bar_) {
    bar_.aaa++;
}

function foo(barBaz) {
    for (barBaz.aaa in baz) {}
}

function foo(barBaz) {
    for (barBaz.aaa of baz) {}
}

:::

When Not To Use It

If you want to allow assignment to function parameters, then you can safely disable this rule.

Strict mode code doesn't sync indices of the arguments object with each parameter binding. Therefore, this rule is not necessary to protect against arguments object mutation in ESM modules or other strict mode functions. Source: http://eslint.org/docs/rules/

title: array-callback-return

rule_type: problem

Array has several methods for filtering, mapping, and folding. If we forget to write return statement in a callback of those, it's probably a mistake. If you don't want to use a return or don't need the returned results, consider using .forEach instead.

// example: convert ['a', 'b', 'c'] --> {a: 0, b: 1, c: 2}
var indexMap = myArray.reduce(function(memo, item, index) {
  memo[item] = index;
}, {}); // Error: cannot set property 'b' of undefined

Rule Details

This rule enforces usage of return statement in callbacks of array's methods. Additionally, it may also enforce the forEach array method callback to not return a value by using the checkForEach option.

This rule finds callback functions of the following methods, then checks usage of return statement.

• Array.from
• Array.prototype.every
• Array.prototype.filter
• Array.prototype.find
• Array.prototype.findIndex
• Array.prototype.findLast
• Array.prototype.findLastIndex
• Array.prototype.flatMap
• Array.prototype.forEach (optional, based on checkForEach parameter)
• Array.prototype.map
• Array.prototype.reduce
• Array.prototype.reduceRight
• Array.prototype.some
• Array.prototype.sort
• Array.prototype.toSorted
• And above of typed arrays.

Examples of incorrect code for this rule:

:::incorrect

/*eslint array-callback-return: "error"*/

var indexMap = myArray.reduce(function(memo, item, index) {
    memo[item] = index;
}, {});

var foo = Array.from(nodes, function(node) {
    if (node.tagName === "DIV") {
        return true;
    }
});

var bar = foo.filter(function(x) {
    if (x) {
        return true;
    } else {
        return;
    }
});

:::

Examples of correct code for this rule:

:::correct

/*eslint array-callback-return: "error"*/

var indexMap = myArray.reduce(function(memo, item, index) {
    memo[item] = index;
    return memo;
}, {});

var foo = Array.from(nodes, function(node) {
    if (node.tagName === "DIV") {
        return true;
    }
    return false;
});

var bar = foo.map(node => node.getAttribute("id"));

:::

Options

This rule accepts a configuration object with three options:

• "allowImplicit": false (default) When set to true, allows callbacks of methods that require a return value to implicitly return undefined with a return statement containing no expression.
• "checkForEach": false (default) When set to true, rule will also report forEach callbacks that return a value.
• "allowVoid": false (default) When set to true, allows void in forEach callbacks, so rule will not report the return value with a void operator.

Note: { "allowVoid": true } works only if checkForEach option is set to true.

allowImplicit

Examples of correct code for the { "allowImplicit": true } option:

:::correct

/*eslint array-callback-return: ["error", { allowImplicit: true }]*/
var undefAllTheThings = myArray.map(function(item) {
    return;
});

:::

checkForEach

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

:::incorrect

/*eslint array-callback-return: ["error", { checkForEach: true }]*/

myArray.forEach(function(item) {
    return handleItem(item);
});

myArray.forEach(function(item) {
    if (item < 0) {
        return x;
    }
    handleItem(item);
});

myArray.forEach(function(item) {
    if (item < 0) {
        return void x;
    }
    handleItem(item);
});

myArray.forEach(item => handleItem(item));

myArray.forEach(item => void handleItem(item));

myArray.forEach(item => {
    return handleItem(item);
});

myArray.forEach(item => {
    return void handleItem(item);
});

:::

Examples of correct code for the { "checkForEach": true } option:

:::correct

/*eslint array-callback-return: ["error", { checkForEach: true }]*/

myArray.forEach(function(item) {
    handleItem(item)
});

myArray.forEach(function(item) {
    if (item < 0) {
        return;
    }
    handleItem(item);
});

myArray.forEach(function(item) {
    handleItem(item);
    return;
});

myArray.forEach(item => {
    handleItem(item);
});

:::

allowVoid

Examples of correct code for the { "allowVoid": true } option:

:::correct

/*eslint array-callback-return: ["error", { checkForEach: true, allowVoid: true }]*/

myArray.forEach(item => void handleItem(item));

myArray.forEach(item => {
    return void handleItem(item);
});

myArray.forEach(item => {
    if (item < 0) {
        return void x;
    }
    handleItem(item);
});

:::

Known Limitations

This rule checks callback functions of methods with the given names, even if the object which has the method is not an array.

When Not To Use It

If you don't want to warn about usage of return statement in callbacks of array's methods, then it's safe to 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/

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/

title: no-param-reassign ruletype: suggestion furtherreading:

- https://spin.atomicobject.com/2011/04/10/javascript-don-t-reassign-your-function-arguments/

Assignment to variables declared as function parameters can be misleading and lead to confusing behavior, as modifying function parameters will also mutate the arguments object when not in strict mode (see When Not To Use It below). Often, assignment to function parameters is unintended and indicative of a mistake or programmer error.

This rule can be also configured to fail when function parameters are modified. Side effects on parameters can cause counter-intuitive execution flow and make errors difficult to track down.

Rule Details

This rule aims to prevent unintended behavior caused by modification or reassignment of function parameters.

Examples of incorrect code for this rule:

::: incorrect

/*eslint no-param-reassign: "error"*/

function foo(bar) {
    bar = 13;
}

function foo(bar) {
    bar++;
}

function foo(bar) {
    for (bar in baz) {}
}

function foo(bar) {
    for (bar of baz) {}
}

:::

Examples of correct code for this rule:

::: correct

/*eslint no-param-reassign: "error"*/

function foo(bar) {
    var baz = bar;
}

:::

Options

This rule takes one option, an object, with a boolean property "props", and arrays "ignorePropertyModificationsFor" and "ignorePropertyModificationsForRegex". "props" is false by default. If "props" is set to true, this rule warns against the modification of parameter properties unless they're included in "ignorePropertyModificationsFor" or "ignorePropertyModificationsForRegex", which is an empty array by default.

props

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

::: correct

/*eslint no-param-reassign: ["error", { "props": false }]*/

function foo(bar) {
    bar.prop = "value";
}

function foo(bar) {
    delete bar.aaa;
}

function foo(bar) {
    bar.aaa++;
}

function foo(bar) {
    for (bar.aaa in baz) {}
}

function foo(bar) {
    for (bar.aaa of baz) {}
}

:::

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

::: incorrect

/*eslint no-param-reassign: ["error", { "props": true }]*/

function foo(bar) {
    bar.prop = "value";
}

function foo(bar) {
    delete bar.aaa;
}

function foo(bar) {
    bar.aaa++;
}

function foo(bar) {
    for (bar.aaa in baz) {}
}

function foo(bar) {
    for (bar.aaa of baz) {}
}

:::

Examples of correct code for the { "props": true } option with "ignorePropertyModificationsFor" set:

::: correct

/*eslint no-param-reassign: ["error", { "props": true, "ignorePropertyModificationsFor": ["bar"] }]*/

function foo(bar) {
    bar.prop = "value";
}

function foo(bar) {
    delete bar.aaa;
}

function foo(bar) {
    bar.aaa++;
}

function foo(bar) {
    for (bar.aaa in baz) {}
}

function foo(bar) {
    for (bar.aaa of baz) {}
}

:::

Examples of correct code for the { "props": true } option with "ignorePropertyModificationsForRegex" set:

::: correct

/*eslint no-param-reassign: ["error", { "props": true, "ignorePropertyModificationsForRegex": ["^bar"] }]*/

function foo(barVar) {
    barVar.prop = "value";
}

function foo(barrito) {
    delete barrito.aaa;
}

function foo(bar_) {
    bar_.aaa++;
}

function foo(barBaz) {
    for (barBaz.aaa in baz) {}
}

function foo(barBaz) {
    for (barBaz.aaa of baz) {}
}

:::

When Not To Use It

If you want to allow assignment to function parameters, then you can safely disable this rule.

Strict mode code doesn't sync indices of the arguments object with each parameter binding. Therefore, this rule is not necessary to protect against arguments object mutation in ESM modules or other strict mode functions. 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/