Disallow assignment to native objects or read-only global variables (no-global-assign)

禁止对原生对象或只读的全局对象进行赋值 (no-global-assign)

The "extends": "eslint:recommended" property in a configuration file enables this rule.

配置文件中的 "extends": "eslint:recommended" 属性启用了此规则。

JavaScript environments contain a number of built-in global variables, such as window in browsers and process in Node.js. In almost all cases, you don’t want to assign a value to these global variables as doing so could result in losing access to important functionality. For example, you probably don’t want to do this in browser code:

JavaScript 环境包含很多内置的全局变量，比如浏览器环境的 window 和 Node.js 中的 process。在几乎所有情况下，你都不希望给全局变量赋值，因为这样做可能会到导致无法访问到重要的功能。例如，你可能不想在浏览器代码中这样做：

window = {};

While examples such as window are obvious, there are often hundreds of built-in global objects provided by JavaScript environments. It can be hard to know if you’re assigning to a global variable or not.

虽然像 window 这样的例子很明显，但是 JavaScript 环境还提供了数百个内置全局对象。很难知道你是否对一个去全局变量进行了赋值。

Rule Details

This rule disallows modifications to read-only global variables.

该规则禁止修改只读的全局变量。

ESLint has the capability to configure global variables as read-only.

ESLint 可以配置全局变量为只读。

Examples of incorrect code for this rule:

错误代码示例：

/*eslint no-global-assign: "error"*/

Object = null
undefined = 1

/*eslint no-global-assign: "error"*/
/*eslint-env browser*/

window = {}
length = 1
top = 1

/*eslint no-global-assign: "error"*/
/*globals a:false*/

a = 1

Examples of correct code for this rule:

正确示例：

/*eslint no-global-assign: "error"*/

a = 1
var b = 1
b = 2

/*eslint no-global-assign: "error"*/
/*eslint-env browser*/

onload = function() {}

/*eslint no-global-assign: "error"*/
/*globals a:true*/

a = 1

Options

This rule accepts an exceptions option, which can be used to specify a list of builtins for which reassignments will be allowed:

该规则接受一个 exceptions 选项，可以用来指定允许进行赋值的内置对象列表：

{
    "rules": {
        "no-global-assign": ["error", {"exceptions": ["Object"]}]
    }
}

When Not To Use It

If you are trying to override one of the native objects.

如果你打算覆盖一个原生对象，你可以不使用此规则。

Version

This rule was introduced in ESLint 3.3.0.

该规则在 ESLint 3.3.0 中被引入。