Prototypes in Javascript

[Jim12345]

Hello,

 

I have a question about prototypes. It seems to me I always encounter a new method being added to an object after the fact. For example this code below runs fine.

<script>var GameObject = function(width, height) { this.x = Math.floor((Math.random() ) + 1); this.y = Math.floor((Math.random() ) + 1); this.width = width; this.height = height; this.car='AMC'; return this;};GameObject.prototype = { draw: function() { return (this.width); }};var n = new GameObject(2200,400);console.log(n.draw());</script>

 

But what I want to do is right from the get go, have the method draw as part of the protoype, this I can't figure out. So what would the code look like?

 

Thanks,

Jim P.

[Don E]

Have you tried adding this.draw = function(){ // code to run here }; to the var GameObject function(object)?

[Jim12345]

Don,

 

I was trying to do this:

draw = function(){ return (this.width); };

 

Instead of this:

this.draw = function(){ return (this.width); };

 

Thanks,

Jim P.

[Ingolme]

You need the this keyword unless you only want the method to be accessible from inside the object.

var GameObject = function(...) {   ...   this.draw = function() {      -   }}

[Jim12345]

Ah OK Thanks Foxy Mod so a private function not accessible to the outside world? Meaning you can't call it from outside it's scope?

[justsomeguy]

More or less, yeah.