Require === and !== (eqeqeq)

要求使用 === 和 !== (eqeqeq)

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

命令行中的 --fix 选项可以自动修复一些该规则报告的问题。

It is considered good practice to use the type-safe equality operators === and !== instead of their regular counterparts == and !=.

使用类型安全的 ===!== 操作符代替 ==!= 操作符是一个很好的实践。

The reason for this is that == and != do type coercion which follows the rather obscure Abstract Equality Comparison Algorithm. For instance, the following statements are all considered true:

这样做的原因是,==!= 遵循 Abstract Equality Comparison Algorithm 作强制转型。例如,以下语句被认为是 true

If one of those occurs in an innocent-looking statement such as a == b the actual problem is very difficult to spot.

如果它们中的任何一个出现在一个看上去无害的语句中,比如 a == b ,那么实际的问题是很难被发现的。

Rule Details

This rule is aimed at eliminating the type-unsafe equality operators.

该规则旨在消除非类型安全的相等操作符。

Examples of incorrect code for this rule:

错误 代码示例:

/*eslint eqeqeq: "error"*/

if (x == 42) { }

if ("" == text) { }

if (obj.getStuff() != undefined) { }

The --fix option on the command line automatically fixes some problems reported by this rule. A problem is only fixed if one of the operands is a typeof expression, or if both operands are literals with the same type.

命令行中的 --fix 选项可以自动修复该规则报告的一些问题。该规则唯一问题是只修复操作数之一是 typeof 表达式的或操作数是相同类型的字面量。

Options

always

The "always" option (default) enforces the use of === and !== in every situation (except when you opt-in to more specific handling of null [see below]).

选项 "always"(默认)强制在任何情况下都使用 ===!== (除非你选择对 null 有更具体的处理[见下文])。

Examples of incorrect code for the "always" option:

选项 "always"错误 代码示例:

/*eslint eqeqeq: ["error", "always"]*/

a == b
foo == true
bananas != 1
value == undefined
typeof foo == 'undefined'
'hello' != 'world'
0 == 0
true == true
foo == null

Examples of correct code for the "always" option:

选项 "always"正确 代码示例:

/*eslint eqeqeq: ["error", "always"]*/

a === b
foo === true
bananas !== 1
value === undefined
typeof foo === 'undefined'
'hello' !== 'world'
0 === 0
true === true
foo === null

This rule optionally takes a second argument, which should be an object with the following supported properties:

该规则可以有第二个参数,是个对象,支持以下属性:

smart

The "smart" option enforces the use of === and !== except for these cases:

选项 "smart" 除了以下这些情况外,强制使用 ===!==

Examples of incorrect code for the "smart" option:

选项 "always"错误 代码示例:

/*eslint eqeqeq: ["error", "smart"]*/

// comparing two variables requires ===
a == b

// only one side is a literal
foo == true
bananas != 1

// comparing to undefined requires ===
value == undefined

Examples of correct code for the "smart" option:

选项 "smart"正确 代码示例:

/*eslint eqeqeq: ["error", "smart"]*/

typeof foo == 'undefined'
'hello' != 'world'
0 == 0
true == true
foo == null

allow-null

Deprecated: Instead of using this option use “always” and pass a “null” option property with value “ignore”. This will tell eslint to always enforce strict equality except when comparing with the null literal.

弃用: 使用 “always”,然后传一个 “null” 选项,属性值为 “ignore” 代替。这将告诉 eslint 除了与 null 字面量进行比较时,总是强制使用绝对相等。

["error", "always", {"null": "ignore"}]

When Not To Use It

If you don’t want to enforce a style for using equality operators, then it’s safe to disable this rule.

如果你不想强制使用相等操作符,可以禁用此规则。

Version

This rule was introduced in ESLint 0.0.2.

该规则在 ESLint 0.0.2 中被引入。

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