"this" in JavaScript

Question

I'm trying to understand the syntax of how to put together a JavaScript function as an object.

Q: Is this the right way to do it?

The reason why I ask is because I'm looking at it in Firebug and I was hoping to be able to drill down and see the value of myVar and myVariable, but instead Firebug only says that "this" is an object Object.

var myObject = {
    init: function() {
        var myVar = 1;
        myObject.myVariable = 2;
        console.log('"this" when called as an object: ' + this);
    }
}
myObject.init();

Also, what's the funny little syntax to call it directly upon declaration? Something about (), but when I remove the last line and put () at the end of the declaration, I get a syntax error.

score 3 · Accepted Answer · answered Dec 27 '10 at 18:48

3

This will create a string:

'"this" when called as an object: ' + this

But this is not a string, so its toString() prototype gets called. That's why you only see [object Object].

If you want to have Firebug display the actual object, do a simple console.log(this) or to see the contents directly use console.dir(this).

answered Dec 27 '10 at 18:48

Ivo Wetzel

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By replacing + with a comma, I was able to see "this" in a much better light. Thanks Wetzel! – Phillip Senn Dec 27 '10 at 19:20

score 2 · Answer 2 · answered Dec 27 '10 at 18:51

The "funny little syntax" doesn't really apply here, because you're not really creating a "function object" — that's just an object with a property whose value is a reference to a function object.

However, though it's been done to death on Stackoverflow, you're probably talking about something like this:

var myobject = (function() {
  var something = { whatever: "for example" };
  return {
    init: function() {
      this.foo = "hello";
      // initialize
    },
    getSomething: function() { return something.whatever; }
  };
})();

Now "myobject" is initialized by a call to an anonymous function, which will be thrown away right after that statement. The closure formed by the function invocation, however, remains alive.

"though it's been done to death on Stackoverflow".
I'm not sure I even know how to frame the question so that I can see similar questions. — Phillip Senn, Dec 27 '10 at 18:58
Well I tried a question about "this" and the SO search thing found [this old question about immediately-invoked anonymous functions](http://stackoverflow.com/questions/1634268/explain-javascripts-encapsulated-anonymous-function-syntax) — Pointy, Dec 27 '10 at 19:06

score 1 · Answer 3 · answered Dec 27 '10 at 18:50

1

Here is a nice reference for JavaScript object creation

answered Dec 27 '10 at 18:50

brildum

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"this" in JavaScript

3 Answers3