What is the meaning of the javascript word this when it is used as an array?

Question

I see statements like this inside a quojs javascript library:

return r(e,this[0].className)

or

return this[0].style[e]||n(this[0],e)

I know from the documentation that this refers to the "global object." But what does the array mean? The array of properties of the global object?

You have to track down the context. `this` depends on how the function is called, it's dynamic, and can be changed at runtime. — elclanrs, Dec 05 '13 at 00:40
intereting question, heres another answer about what exactly 'this' might refer to http://stackoverflow.com/questions/133973/how-does-this-keyword-work-within-a-javascript-object-literal — actual_kangaroo, Dec 05 '13 at 00:41
From looking at the code though, I would say `this` is a NodeList. — elclanrs, Dec 05 '13 at 00:45
The MDN documentation also explains which other values `this` can have. — Felix Kling, Dec 05 '13 at 00:56

Alex Wayne · Accepted Answer · 2013-12-05T00:50:42.570

2

The value of this depends on many things, and you can't tell from that snippet of code.

For example:

var person = {
  name: "Bob",
  sayHi: function() {
    alert(this.name + " says hi!");
  }
};

person.sayHi();

In this example, this refers to person when the sayHi() method is invoked. But If all I posted was this:

alert(this.name + " says hi!");

There would be no way to tell what the value of this is. this is known as the context, so the context in which it appears is important!

edited Dec 05 '13 at 00:50

answered Dec 05 '13 at 00:42

Alex Wayne

what are the contexts in which this can take on the properties of an array? – bernie2436 Dec 05 '13 at 09:53
When an array is the receiver of a method invocation. `myArray.foo()`, `this` is equal to `myArray` within `foo`. But _any_ javascript object (which includes arrays) can be access with the `obj[key]` notation. – Alex Wayne Dec 05 '13 at 18:20

1 Answers1