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163

What does return this do within a javascript function?

rated 0 times [ 164] [ 1] / answers: 1 / hits: 37193 / 13 Years ago, mon, november 28, 2011, 12:00:00

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.

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bryonk

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answered 13 Years ago gregoriocoya · Accepted Answer

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/