"this" in javascript

[Rajesh Khan]

Hi I was reading up on creating objects in javascript and I am a bit confused with the "this" keyword.
Normally in C++ and java the this keyword refers to the current "instance" of the class what about javascript. As in this example

person = new Object()
person.name = "Tim Scarfe"
person.height = "6Ft"

person.run = function() {
	this.state = "running"
	this.speed = "4ms^-1"
}

does "this.state" statement create a member variable ?? Some articles say its the window object. But I am confused any help or suggestions would be appreciated..

[Bear Bibeault]

The worse thing you can possibly do in trying to understand JavaScript is to try to pretend it's Java. (Or C++) It's not. Not even close.

Within a JavaScript function, the this reference is called the function context. And unlike in non-functional languages such as Java, what the function context refers to is not a factor of how the function is declared, but on how it is called.

When using JavaScript in an object-oriented fashion, it's customary to call the method through its reference. In your example, that would be: person.run(); And in that case, this will point to person.

However, calling the function in other ways will result in a different function context. It could be window, or it could actually be any object of your choosing.