Prototype function declaration

Question

I have defined the function:

var Test = function(){

};

Test.prototype={

   getColor: function(){
         return "red";
   },

   createCar: function(){
      var color = this.getColor(); //ERROR: this.getColor is not a function
      ...
   },

   getCar: function(){
      return new CarFactory(1, this.createCar);
   }

}

As you saw, I have defined three prototype functions: getColor() , createCar() and getCar().

Inside createCar() function I called getColor(),

In function getCar(), I use this.createCar as a parameter of CarFactory constructor. I got the error:

"this.getColor is not a function"

in the above indicated place, why this error? How to get rid of this error?

Answer 1

I think you might not be making a Test object and invoking it properly. I pasted your snippet into a test page, then added:

var obj = new Test();
console.log(obj.getColor());
// Outputs 'red'
obj.createCar();
// Does not throw an error. 

Replacing your ... with console.log(color); revealed the correct result 'red' in my test.

http://jsfiddle.net/2F5zz