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enforce line breaks between array elements (array-element-newline)

The --fix option on the command line can automatically fix some of the problems reported by this rule.

A number of style guides require or disallow line breaks between array elements.

Rule Details

This rule enforces line breaks between array elements.

Options

This rule has either a string option:

  • "always" (default) requires line breaks between array elements
  • "never" disallows line breaks between array elements
  • "consistent" requires consistent usage of linebreaks between array elements

Or an object option (Requires line breaks if any of properties is satisfied. Otherwise, disallows line breaks):

  • "multiline": <boolean> requires line breaks if there are line breaks inside elements. If this is false, this condition is disabled.
  • "minItems": <number> requires line breaks if the number of elements is at least the given integer. If this is 0, this condition will act the same as the option "always". If this is null (the default), this condition is disabled.

Alternatively, different configurations can be specified for array expressions and array patterns:

{
    "array-element-newline": ["error", {
        "ArrayExpression": "consistent",
        "ArrayPattern": { "minItems": 3 },
    }]
}
  • "ArrayExpression" configuration for array expressions (if unspecified, this rule will not apply to array expressions)
  • "ArrayPattern" configuration for array patterns of destructuring assignments (if unspecified, this rule will not apply to array patterns)

always

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

/*eslint array-element-newline: ["error", "always"]*/

var c = [1, 2];
var d = [1, 2, 3];
var e = [
    function foo() {
        dosomething();
    }, function bar() {
        dosomething();
    }
];

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

/*eslint array-element-newline: ["error", "always"]*/

var a = [];
var b = [1];
var c = [1,
    2];
var d = [1,
    2,
    3];
var e = [
    function foo() {
        dosomething();
    },
    function bar() {
        dosomething();
    }
];

never

Examples of incorrect code for this rule with the "never" option:

/*eslint array-element-newline: ["error", "never"]*/

var c = [
    1,
    2
];
var d = [
    1,
    2,
    3
];
var e = [
    function foo() {
        dosomething();
    },
    function bar() {
        dosomething();
    }
];

Examples of correct code for this rule with the "never" option:

/*eslint array-element-newline: ["error", "never"]*/

var a = [];
var b = [1];
var c = [1, 2];
var d = [1, 2, 3];
var e = [
    function foo() {
        dosomething();
    }, function bar() {
        dosomething();
    }
];

consistent

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

/*eslint array-element-newline: ["error", "consistent"]*/

var a = [
    1, 2,
    3
];
var b = [
    function foo() {
        dosomething();
    }, function bar() {
        dosomething();
    },
    function baz() {
        dosomething();
    }
];

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

/*eslint array-element-newline: ["error", "consistent"]*/

var a = [];
var b = [1];
var c = [1, 2];
var d = [1, 2, 3];
var e = [
    1,
    2
];
var f = [
    1,
    2,
    3
];
var g = [
    function foo() {
        dosomething();
    }, function bar() {
        dosomething();
    }, function baz() {
        dosomething();
    }
];
var h = [
    function foo() {
        dosomething();
    },
    function bar() {
        dosomething();
    },
    function baz() {
        dosomething();
    }
];

multiline

Examples of incorrect code for this rule with the { "multiline": true } option:

/*eslint array-element-newline: ["error", { "multiline": true }]*/

var d = [1,
    2, 3];
var e = [
    function foo() {
        dosomething();
    }, function bar() {
        dosomething();
    }
];

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

/*eslint array-element-newline: ["error", { "multiline": true }]*/

var a = [];
var b = [1];
var c = [1, 2];
var d = [1, 2, 3];
var e = [
    function foo() {
        dosomething();
    },
    function bar() {
        dosomething();
    }
];

minItems

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

/*eslint array-element-newline: ["error", { "minItems": 3 }]*/

var c = [1,
    2];
var d = [1, 2, 3];
var e = [
    function foo() {
        dosomething();
    },
    function bar() {
        dosomething();
    }
];

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

/*eslint array-element-newline: ["error", { "minItems": 3 }]*/

var a = [];
var b = [1];
var c = [1, 2];
var d = [1,
    2,
    3];
var e = [
    function foo() {
        dosomething();
    }, function bar() {
        dosomething();
    }
];

multiline and minItems

Examples of incorrect code for this rule with the { "multiline": true, "minItems": 3 } options:

/*eslint array-element-newline: ["error", { "multiline": true, "minItems": 3 }]*/

var c = [1,
2];
var d = [1, 2, 3];
var e = [
    function foo() {
        dosomething();
    }, function bar() {
        dosomething();
    }
];

Examples of correct code for this rule with the { "multiline": true, "minItems": 3 } options:

/*eslint array-element-newline: ["error", { "multiline": true, "minItems": 3 }]*/

var a = [];
var b = [1];
var c = [1, 2];
var d = [1,
    2,
    3];
var e = [
    function foo() {
        dosomething();
    },
    function bar() {
        dosomething();
    }
];

ArrayExpression and ArrayPattern

Examples of incorrect code for this rule with the { "ArrayExpression": "always", "ArrayPattern": "never" } options:

/*eslint array-element-newline: ["error", { "ArrayExpression": "always", "ArrayPattern": "never" }]*/

var a = [1, 2];
var b = [1, 2, 3];
var c = [
    function foo() {
        dosomething();
    }, function bar() {
        dosomething();
    }
];

var [d,
    e] = arr;
var [f,
    g,
    h] = arr;
var [i = function foo() {
  dosomething()
},
j = function bar() {
  dosomething()
}] = arr

Examples of correct code for this rule with the { "ArrayExpression": "always", "ArrayPattern": "never" } options:

/*eslint object-curly-newline: ["error", { "ArrayExpression": "always", "ArrayPattern": "never" }]*/

var a = [1,
    2];
var b = [1,
    2,
    3];
var c = [
    function foo() {
        dosomething();
    },
    function bar() {
        dosomething();
    }
];

var [d, e] = arr
var [f, g, h] = arr
var [i = function foo() {
    dosomething()
}, j = function bar() {
    dosomething()
}] = arr

When Not To Use It

If you don't want to enforce linebreaks between array elements, don't enable this rule.

Compatibility

Version

This rule was introduced in ESLint 4.0.0-rc.0.

Resources

© JS Foundation and other contributors
Licensed under the MIT License.
https://eslint.org/docs/rules/array-element-newline