Disallow use of the void operator. (no-void)

禁止使用void操作符 (no-void)

The void operator takes an operand and returns undefined: void expression will evaluate expression and return undefined. It can be used to ignore any side effects expression may produce:

void 操作符需要一个运算对象并且返回 undefined：void expression 会计算 expression 并返回 undefined。它可以用来忽略 expression 产生的任何副作用。

The common case of using void operator is to get a “pure” undefined value as prior to ES5 the undefined variable was mutable:

使用 void 操作符的通常情况是要得到一个单纯的 undefined 值，因为之前的 ES5 undefined 值是可变的:

// will always return undefined
(function(){
    return void 0;
})();

// will return 1 in ES3 and undefined in ES5+
(function(){
    undefined = 1;
    return undefined;
})();

// will throw TypeError in ES5+
(function(){
    'use strict';
    undefined = 1;
})();

Another common case is to minify code as void 0 is shorter than undefined:

另外一种情况是缩减代码量因为 void 0 比 undefined 要简短:

foo = void 0;
foo = undefined;

When used with IIFE (immediately-invoked function expression), void can be used to force the function keyword to be treated as an expression instead of a declaration:

当在 IIFE (立即调用函数表达式)时被使用时,void 可以用来强制 function 关键字被当作成表达式而不是声明:

var foo = 1;
void function(){ foo = 1; }() // will assign foo a value of 1
+function(){ foo = 1; }() // same as above

function(){ foo = 1; }() // will throw SyntaxError

Some code styles prohibit void operator, marking it as non-obvious and hard to read.

一些代码风格禁止使用 void 操作符，把它标记为不明显的，难以阅读的。

Rule Details

This rule aims to eliminate use of void operator.

此规则目的在于排除使用 void 操作符。

Examples of incorrect code for this rule:

错误 代码示例：

/*eslint no-void: "error"*/

void foo

var foo = void bar();

When Not To Use It

If you intentionally use the void operator then you can disable this rule.

如果你有意使用 void 操作符，可以禁用此规则。

Further Reading

Version

This rule was introduced in ESLint 0.8.0.

该规则在 ESLint 0.8.0 中被引入。

Resources