title | rule_type |
---|---|
no-useless-computed-key |
suggestion |
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"};
This rule disallows unnecessary usage of computed property keys.
Examples of incorrect code for this rule:
::: incorrect
/*eslint no-useless-computed-key: "error"*/
var a = { ['0']: 0 };
var a = { ['0+1,234']: 0 };
var a = { [0]: 0 };
var a = { ['x']: 0 };
var a = { ['x']() {} };
class Foo {
["foo"] = "bar";
[0]() {}
['a']() {}
get ['b']() {}
set ['c'](value) {}
static ["foo"] = "bar";
static ['a']() {}
}
:::
Examples of correct code for this rule:
::: correct
/*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 };
class Foo {
"foo" = "bar";
0() {}
'a'() {}
get 'b'() {}
set 'c'(value) {}
static "foo" = "bar";
static 'a'() {}
}
:::
Examples of additional correct code for this rule:
::: correct
/*eslint no-useless-computed-key: "error"*/
var c = {
"__proto__": foo, // defines object's prototype
["__proto__"]: bar // defines a property named "__proto__"
};
class Foo {
["constructor"]; // instance field named "constructor"
"constructor"() {} // the constructor of this class
["constructor"]() {} // method named "constructor"
static ["constructor"]; // static field named "constructor"
static ["prototype"]; // runtime error, it would be a parsing error without `[]`
}
:::
This rule has an object option:
enforceForClassMembers
set tofalse
disables this rule for class members (Defaulttrue
).
By default, this rule also checks class declarations and class expressions,
as the default value for enforceForClassMembers
is true
.
When enforceForClassMembers
is set to false
, the rule will allow unnecessary computed keys inside of class fields, class methods, class getters, and class setters.
Examples of incorrect code for this rule with the { "enforceForClassMembers": false }
option:
::: incorrect
/*eslint no-useless-computed-key: ["error", { "enforceForClassMembers": false }]*/
const obj = {
["foo"]: "bar",
[42]: "baz",
['a']() {},
get ['b']() {},
set ['c'](value) {}
};
:::
Examples of correct code for this rule with the { "enforceForClassMembers": false }
option:
::: correct
/*eslint no-useless-computed-key: ["error", { "enforceForClassMembers": false }]*/
class SomeClass {
["foo"] = "bar";
[42] = "baz";
['a']() {}
get ['b']() {}
set ['c'](value) {}
static ["foo"] = "bar";
static ['baz']() {}
}
:::
If you don't want to be notified about unnecessary computed property keys, you can safely disable this rule.