wrap-iife.md

规则名	规则类型
wrap-iife	layout

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

规则详解

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

配置项

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

String option:

• "outside" enforces always wrapping the call expression. The default is "outside".
• "inside" enforces always wrapping the function expression.
• "any" enforces always wrapping, but allows either style.

Object option:

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

outside

选项 default "outside" 的 错误 代码示例：

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

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

选项 default "outside" 的 正确 代码示例：

::: correct

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

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

inside

选项 "inside" 的 错误 代码示例：

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

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

选项 "inside" 的 正确 代码示例：

::: correct

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

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

any

选项 "any" 的 错误 代码示例：

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

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

选项 "any" 的 正确 代码示例：

::: correct

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

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

functionPrototypeMethods

选项 "inside", { "functionPrototypeMethods": true } 的 错误 代码示例：

/* 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))

选项 "inside", { "functionPrototypeMethods": true } 的 正确 代码示例：

::: correct

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

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