What does "return this" do within a javascript function?

Question

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

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

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

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.

Answer 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:

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

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

But requires less typing.

Here is a more complete example:

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/