wrap-iife

要求在立即 function 调用周围加上括号

你可以立即调用函数表达式，但不能调用函数声明。创建立即调用函数表达式 (IIFE) 的常用技术是将函数声明封装在括号中。左括号导致包含的函数被解析为表达式，而不是声明。

¥You can immediately invoke function expressions, but not function declarations. A common technique to create an immediately-invoked function expression (IIFE) is to wrap a function declaration in parentheses. The opening parentheses causes the contained function to be parsed as an expression, rather than a declaration.

// function expression could be unwrapped
var x = function () { return { y: 1 };}();

// function declaration must be wrapped
function () { /* side effects */ }(); // SyntaxError
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规则详情

¥Rule Details

此规则要求所有立即调用的函数表达式都用括号括起来。

¥This rule requires all immediately-invoked function expressions to be wrapped in parentheses.

选项

¥Options

该规则有两个选项，一个字符串选项和一个对象选项。

¥This rule has two options, a string option and an object option.

字符串选项：

¥String option:

• "outside" 强制始终封装调用表达式。默认值为 "outside"。

  ¥"outside" enforces always wrapping the call expression. The default is "outside".

• "inside" 强制始终封装函数表达式。

  ¥"inside" enforces always wrapping the function expression.

• "any" 强制始终换行，但允许任一样式。

  ¥"any" enforces always wrapping, but allows either style.

对象选项：

¥Object option:

• "functionPrototypeMethods": true 还强制封装使用 .call 和 .apply 调用的函数表达式。默认值为 false。

  ¥"functionPrototypeMethods": true additionally enforces wrapping function expressions invoked using .call and .apply. The default is false.

outside

默认 "outside" 选项的错误代码示例：

¥Examples of incorrect code for the default "outside" option:

/*eslint wrap-iife: ["error", "outside"]*/

var x = function () { return { y: 1 };}(); // unwrapped
var x = (function () { return { y: 1 };})(); // wrapped function expression
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默认 "outside" 选项的正确代码示例：

¥Examples of correct code for the default "outside" option:

/*eslint wrap-iife: ["error", "outside"]*/

var x = (function () { return { y: 1 };}()); // wrapped call expression
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inside

"inside" 选项的错误代码示例：

¥Examples of incorrect code for the "inside" option:

/*eslint wrap-iife: ["error", "inside"]*/

var x = function () { return { y: 1 };}(); // unwrapped
var x = (function () { return { y: 1 };}()); // wrapped call expression
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"inside" 选项的正确代码示例：

¥Examples of correct code for the "inside" option:

/*eslint wrap-iife: ["error", "inside"]*/

var x = (function () { return { y: 1 };})(); // wrapped function expression
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any

"any" 选项的错误代码示例：

¥Examples of incorrect code for the "any" option:

/*eslint wrap-iife: ["error", "any"]*/

var x = function () { return { y: 1 };}(); // unwrapped
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"any" 选项的正确代码示例：

¥Examples of correct code for the "any" option:

/*eslint wrap-iife: ["error", "any"]*/

var x = (function () { return { y: 1 };}()); // wrapped call expression
var x = (function () { return { y: 1 };})(); // wrapped function expression
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functionPrototypeMethods

使用 "inside", { "functionPrototypeMethods": true } 选项的此规则的错误代码示例：

¥Examples of incorrect code for this rule with the "inside", { "functionPrototypeMethods": true } options:

/* eslint wrap-iife: [2, "inside", { functionPrototypeMethods: true }] */

var x = function(){ foo(); }()
var x = (function(){ foo(); }())
var x = function(){ foo(); }.call(bar)
var x = (function(){ foo(); }.call(bar))
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使用 "inside", { "functionPrototypeMethods": true } 选项的此规则的正确代码示例：

¥Examples of correct code for this rule with the "inside", { "functionPrototypeMethods": true } options:

/* eslint wrap-iife: [2, "inside", { functionPrototypeMethods: true }] */

var x = (function(){ foo(); })()
var x = (function(){ foo(); }).call(bar)
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版本

此规则是在 ESLint v0.0.9 中引入。

资源

• 规则源码
• 测试源码