Disallow unnecessary computed property keys in objects and classes (no-useless-computed-key)

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

It's unnecessary to use computed properties with literals such as:

var foo = {["a"]: "b"};

The code can be rewritten as:

var foo = {"a": "b"};

Rule Details

This rule disallows unnecessary usage of computed property keys.

Examples of incorrect code for this rule:

/*eslint no-useless-computed-key: "error"*/
/*eslint-env es6*/

var a = { ['0']: 0 };
var a = { ['0+1,234']: 0 };
var a = { [0]: 0 };
var a = { ['x']: 0 };
var a = { ['x']() {} };

Examples of correct code for this rule:

/*eslint no-useless-computed-key: "error"*/

var c = { 'a': 0 };
var c = { 0: 0 };
var a = { x() {} };
var c = { a: 0 };
var c = { '0+1,234': 0 };

Options

This rule has an object option:

• enforceForClassMembers set to true additionally applies this rule to class members (Default false).

enforceForClassMembers

By default, this rule does not check class declarations and class expressions, as the default value for enforceForClassMembers is false.

When enforceForClassMembers is set to true, the rule will also disallow unnecessary computed keys inside of class methods, getters and setters.

Examples of incorrect code for { "enforceForClassMembers": true }:

/*eslint no-useless-computed-key: ["error", { "enforceForClassMembers": true }]*/

class Foo {
    [0]() {}
    ['a']() {}
    get ['b']() {}
    set ['c'](value) {}

    static ['a']() {}
}

When Not To Use It

If you don't want to be notified about unnecessary computed property keys, you can safely disable this rule.

Version

This rule was introduced in ESLint 2.9.0.

Resources

• Rule source
• Documentation source