Disallow Self Compare (no-self-compare)

禁止自身比较（no-self-compare）

Comparing a variable against itself is usually an error, either a typo or refactoring error. It is confusing to the reader and may potentially introduce a runtime error.

变量与其自身进行比较通常来说是一个错误，要么是打字错误要么是重构错误。它都会给读者造成困扰并且可能会引入运行错误。

The only time you would compare a variable against itself is when you are testing for NaN. However, it is far more appropriate to use typeof x === 'number' && isNaN(x) or the Number.isNaN ES2015 function for that use case rather than leaving the reader of the code to determine the intent of self comparison.

唯一肯能会对变量自身做比较时候是当你在测试变量是否是 NaN。然而，在这种情况下，更适合使用 typeof x === 'number' && isNaN(x) 或者 Number.isNaN ES2015 函数 而不是变量自身比较。

Rule Details

This error is raised to highlight a potentially confusing and potentially pointless piece of code. There are almost no situations in which you would need to compare something to itself.

该规则为了突出一个潜在的令人困惑的、无意义的代码。几乎没有场景需要你比较变量本身。

Examples of incorrect code for this rule:

错误 代码示例：

/*eslint no-self-compare: "error"*/

var x = 10;
if (x === x) {
    x = 20;
}

Version

This rule was introduced in ESLint 0.0.9.

该规则在 ESLint 0.0.9 中被引入。

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