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require or disallow newlines around variable declarations (one-var-declaration-per-line)

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

Some developers declare multiple var statements on the same line:

var foo, bar, baz;

Others prefer to declare one var per line.

var foo,
    bar,
    baz;

Keeping to one of these styles across a project's codebase can help with maintaining code consistency.

Rule Details

This rule enforces a consistent newlines around variable declarations. This rule ignores variable declarations inside for loop conditionals.

Options

This rule has a single string option:

  • "initializations" (default) enforces a newline around variable initializations
  • "always" enforces a newline around variable declarations

initializations

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

/*eslint one-var-declaration-per-line: ["error", "initializations"]*/
/*eslint-env es6*/

var a, b, c = 0;

let a,
    b = 0, c;

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

/*eslint one-var-declaration-per-line: ["error", "initializations"]*/
/*eslint-env es6*/

var a, b;

let a,
    b;

let a,
    b = 0;

always

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

/*eslint one-var-declaration-per-line: ["error", "always"]*/
/*eslint-env es6*/

var a, b;

let a, b = 0;

const a = 0, b = 0;

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

/*eslint one-var-declaration-per-line: ["error", "always"]*/
/*eslint-env es6*/

var a,
    b;

let a,
    b = 0;

Version

This rule was introduced in ESLint 2.0.0-beta.3.

Resources

© JS Foundation and other contributors
Licensed under the MIT License.
https://eslint.org/docs/rules/one-var-declaration-per-line