enforce line breaks after opening and before closing array brackets (array-bracket-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 inside of array brackets.

Rule Details

This rule enforces line breaks after opening and before closing array brackets.

Options

This rule has either a string option:

• "always" requires line breaks inside brackets
• "never" disallows line breaks inside brackets
• "consistent" requires consistent usage of linebreaks for each pair of brackets. It reports an error if one bracket in the pair has a linebreak inside it and the other bracket does not.

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

• "multiline": true (default) requires line breaks if there are line breaks inside elements or between elements. If this is false, this condition is disabled.
• "minItems": null (default) 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.

always

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

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

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

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

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

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

never

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

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

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

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

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

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

consistent

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

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

var a = [1
];
var b = [
    1];
var c = [function foo() {
    dosomething();
}
]
var d = [
    function foo() {
        dosomething();
    }]

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

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

var a = [];
var b = [
];
var c = [1];
var d = [
    1
];
var e = [function foo() {
    dosomething();
}];
var f = [
    function foo() {
        dosomething();
    }
];

multiline

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

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

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

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

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

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

minItems

Examples of incorrect code for this rule with the { "minItems": 2 } option:

/*eslint array-bracket-newline: ["error", { "minItems": 2 }]*/

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

Examples of correct code for this rule with the { "minItems": 2 } option:

/*eslint array-bracket-newline: ["error", { "minItems": 2 }]*/

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

multiline and minItems

Examples of incorrect code for this rule with the { "multiline": true, "minItems": 2 } options:

/*eslint array-bracket-newline: ["error", { "multiline": true, "minItems": 2 }]*/

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

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

/*eslint array-bracket-newline: ["error", { "multiline": true, "minItems": 2 }]*/

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

When Not To Use It

If you don't want to enforce line breaks after opening and before closing array brackets, don't enable this rule.

Compatibility

• JSCS: validateNewlineAfterArrayElements

Related Rules

• array-bracket-spacing

Version

This rule was introduced in ESLint 4.0.0-alpha.1.

Resources

• Rule source
• Documentation source