this in javascript constructor function

Question

function Foo() {  
    alert(this === a);//return false!   **why this is not equal a?**  
}  
var a = new Foo();//create a new object

foo is a constructor,why this in the 'Foo' is not equal with 'a'.

jfriend00 · Accepted Answer · 2011-10-12 08:34:09Z

6

The assignment to the variable a has not yet happened when you're inside the constructor. The sequence of events is:

answered Oct 12, 2011 at 8:34

jfriend00

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3 Comments

@KooiInc alerts true?i run the code in firebug, it alerts false.

@ray: run the exact code string I gave in my previous comment in whatever browser. My code string differs from yours - alert(this*.name* === a);.

@KooiInc - the only reason your code alerts true is because both this.name and a are undefined. That isn't accomplishing anything.

david · Accepted Answer · 2011-10-12 08:37:39Z

-1

i think "this" referring to as a object, but "this.a" is true as that is the object

answered Oct 12, 2011 at 8:37

david

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There is no this.a here. So i don't really get what you're trying to say.

well it look to me as being as ray was trying to check for equality on "a" as "this" was an object of objects