space-before-keywords

Enforces consistent spacing before keywords.

(fixable) The --fix option on the command line automatically fixed problems reported by this rule.

Keywords are syntax elements of JavaScript, such as function and if. These identifiers have special meaning to the language and so often appear in a different color in code editors. As an important part of the language, style guides often refer to the spacing that should be used around keywords. For example, you might have a style guide that says keywords should be always be preceded by spaces, which would mean if-else statements must look like this:

if (foo) {
    // ...
} else {
    // ...
}
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Of course, you could also have a style guide that disallows spaces before keywords.

Rule Details

This rule will enforce consistency of spacing before the keywords if, else, for, while, do, switch, throw, try, catch, finally, with, break, continue, return, function, yield, class and variable declarations (let, const, var) and label statements.

This rule takes one argument: "always" or "never". If "always" then the keywords must be preceded by at least one space. If "never" then no spaces will be allowed before the keywords else, while (do…while), finally and catch. The default value is "always".

This rule will allow keywords to be preceded by an opening curly brace ({). If you wish to alter this behavior, consider using the block-spacing rule.

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

/*eslint space-before-keywords: ["error", "always"]*/
/*eslint-env es6*/

if (foo) {
    // ...
}else {}

const foo = 'bar';let baz = 'qux';

var qux =function bar () {}

function bar() {
    if (foo) {return; }
}
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Examples of correct code for this rule with the default "always" option:

/*eslint space-before-keywords: ["error", "always"]*/
/*eslint-env es6*/

if (foo) {
    // ...
} else {}

(function() {})();

<Foo onClick={function bar() {}} />

for (let foo of ['bar', 'baz', 'qux']) {}
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Examples of incorrect code for this rule with the "never" option:

/*eslint space-before-keywords: ["error", "never"]*/

if (foo) {
    // ...
} else {}

do {

}
while (foo)

try {} finally {}

try {} catch(e) {}
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Examples of correct code for this rule with the "never" option:

/*eslint space-before-keywords: ["error", "never"]*/

if (foo) {
    // ...
}else {}

do {}while (foo)

try {}finally {}

try{}catch(e) {}
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When Not To Use It

If you do not wish to enforce consistency on keyword spacing.

Version

This rule was introduced in ESLint v1.4.0 and removed in v2.0.0-beta.3.

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