什么时候使用匿名JavaScript函数? [英] When to use anonymous JavaScript functions?

问题描述

我试图了解何时使用匿名JavaScript函数.

I'm trying to understand when to use anonymous JavaScript functions.

功能之间的状态差异?说明何时使用它们.

State differences between the functions? Explain when you would use each.

var test1 = function(){
    $("<div />").html("test1").appendTo(body)
};

function test2() {
    $("<div />").html("test2").appendTo(body)
}

我认为答案是，一个使用匿名函数，另一个不替换空的div元素.看起来正确吗?

I think the answer is that one uses anonymous function and the other doesn't to replace an empty div element. Does that seem right?

推荐答案

在您的示例中，它的作用并不大.唯一的区别是，使用function foo() { }声明的函数可随时在同一范围 中的任何位置访问，而使用var foo = function () { }声明的函数只能在 之后的代码中访问.作业已经执行了吗?

In your example it really doesn't make a huge difference. The only difference is that functions declared using function foo() { } are accessible anywhere within the same scope at any time, while functions declared using var foo = function () { } are only accessible after the code that does the assignment has run.

foo(); // ok
function foo() { ... };

bar(); // error, bar is not a function
var bar = function () { ... };
bar(); // ok

通常在不需要命名函数或构造对象的情况下使用匿名函数:

You usually use anonymous functions in cases where you don't need a named function, or where you're constructing objects:

arr.sort(function (a, b) { return a - b; });  // anonymous callback function

function MyObject() {
    this.foo = function () { ... }  // object constructor
}

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