什么“返回此”在javascript函数中做什么？

i wonder, what does "return this" do within a javascript function, what's its purpose? supposing we have the following code:

我想知道，在javascript函数中“返回这个”是做什么的，它的目的是什么？假设我们有以下代码：

Function.prototype.method = function (name, func) {
  this.prototype[name] = func;
  return this;
};

What does "return this" do inside of a function?

什么“返回这个”在函数内部做什么？

I know what code above does, and what is the use of "this" keyword. I just don't know what "return this" does inside of a function.

我知道上面的代码是什么，以及“this”关键字的用途是什么。我只是不知道函数内部有什么“返回这个”。

4 个解决方案

#1

It refers to the object instance on which the method is currently being called. It's used for chaining. For example, you could do something like this:

它指的是当前正在调用该方法的对象实例。它用于链接。例如，你可以这样做：

myObject.foo().bar();

Since foo returns this (a reference to myObject), bar will be called on the object too. This is the same thing as doing

由于foo返回此（对myObject的引用），因此也会在对象上调用bar。这跟做的一样

myObject.foo();
myObject.bar();

But requires less typing.

但需要更少的打字。

Here is a more complete example:

这是一个更完整的例子：

function AnimalSounds() {}

AnimalSounds.prototype.cow = function() {
    alert("moo");
    return this;
}

AnimalSounds.prototype.pig = function() {
    alert("oink");
    return this;
}

AnimalSounds.prototype.dog = function() {
    alert("woof");
    return this;
}

var sounds = new AnimalSounds();

sounds.cow();
sounds.pig();
sounds.dog();

sounds.cow().pig().dog();

http://jsfiddle.net/jUfdr/

4 个解决方案

#1

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