Variable "is not defined" message, why

Question

I have defined a object in a js file:

myobj.js

MyObj={
  
  test: {
     value: {a: 10, b: 7},

     startTest: function(){
         var x = this.value.a;
         var y = this.value.b;
         return {x: x, y: y};
     }
  }
}

In another js file I call this object function:

other.js

mytest = MyObj.test.startTest //assign starTest function to mytest
var a = mytest().x;
var b = mytest().y;

my index.html:

<body>
 <script src="myobj.js"></script>
 <script src="other.js"></script>
</body>

I got the error from Firebug in myobj.js:

"this.value" is not defined in the line "this.value.a;"

Why?

possible duplicate of [Why I got "Undefined" error?](http://stackoverflow.com/questions/5699861/why-i-got-undefined-error) — Mat, Apr 18 '11 at 08:05
This is personal preference: I don't like how you declare MyObj. I prefer "function MyObj(){ [...] }". Same for the startTest inner function: I Prefer "this.startTest = function(){ [...] }". Those are more "standard" ways. Refer to this StackOverflow question with a really good answer: http://stackoverflow.com/questions/1595611/how-to-properly-create-a-custom-object-in-javascript — dmarucco, Apr 18 '11 at 08:07
Don't create a new question. Instead, update your original question with all the information. I mean obviously the code you posted there was not complete, otherwise you would have not get another error... — Felix Kling, Apr 18 '11 at 08:12

score 5 · Accepted Answer · answered Apr 18 '11 at 08:03

5

mytest = MyObj.test.startTest

This gives you a function without context. If you call this function directly then this is window.

You want to all test.startTest() so that this is test

An excellent guide on this

answered Apr 18 '11 at 08:03

Raynos

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Variable "is not defined" message, why

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