Require Consistent This (consistent-this)

要求一致的 This (consistent-this)

It is often necessary to capture the current execution context in order to make it available subsequently. A prominent example of this are jQuery callbacks:

通常，非常有必要获取当前执行环境的上下文以便在后续过程中继续使用。一个常见的例子就是 jQuery 的回调函数：

var that = this;
jQuery('li').click(function (event) {
    // here, "this" is the HTMLElement where the click event occurred
    that.setFoo(42);
});

There are many commonly used aliases for this such as that, self or me. It is desirable to ensure that whichever alias the team agrees upon is used consistently throughout the application.

this 有多个常用的别名，例如 self、that 或 me 。在整个项目中确保团队成员使用同样的别名是一个很有必要的事情。

Rule Details

This rule enforces two things about variables with the designated alias names for this:

该规则指定一个变量作为 this 的别名。它将强制两件事情：

If a variable with a designated name is declared, it must be either initialized (in the declaration) or assigned (in the same scope as the declaration) the value this.
如果一个变量声明为一个指定的名称，它必须初始化（在声明语句中）或被赋值（与声明语句在同一范围内）为 this。
If a variable is initialized or assigned the value this, the name of the variable must be a designated alias.
如果一个变量初始化或被赋值为 this，那么该变量必须是指定的别名。

Options

This rule has one or more string options:

该规则有一个到两个字符串选项：

designated alias names for this (default "that")
为 this 指定别名 (默认 "that")

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

默认选项 "that" 的错误代码示例：

/*eslint consistent-this: ["error", "that"]*/

var that = 42;

var self = this;

that = 42;

self = this;

Examples of correct code for this rule with the default "that" option:

默认选项 "that" 的正确代码示例：

/*eslint consistent-this: ["error", "that"]*/

var that = this;

var self = 42;

var self;

that = this;

foo.bar = this;

Examples of incorrect code for this rule with the default "that" option, if the variable is not initialized:

如果指定的变量没有初始化，默认选项 "that" 的错误代码示例：

/*eslint consistent-this: ["error", "that"]*/

var that;
function f() {
    that = this;
}

Examples of correct code for this rule with the default "that" option, if the variable is not initialized:

如果指定的变量没有初始化，默认选项 "that" 的正确代码示例：

/*eslint consistent-this: ["error", "that"]*/

var that;
that = this;

var foo, that;
foo = 42;
that = this;

When Not To Use It

If you need to capture nested context, consistent-this is going to be problematic. Code of that nature is usually difficult to read and maintain and you should consider refactoring it.

如果你需要获取嵌套的上下文，consistent-this 是会有问题的。这种类型的代码通常很难阅读和维护，你应该考虑重构它。

Version

This rule was introduced in ESLint 0.0.9.