Defined things, not defined again... HTML5 Canvas

[jeffery wright]

Cannot read property 'b_Title' of undefined ... yet it is indeed defined. 

This is the offending code:

	this.p_Button.addEventListener("click", APDHMIDM.bind(this)); // error-free

		function b_Lang(){
			if( IsRussia == 1){
			this.p_Button.b_Title.text = ru_APDHMIDM;
			}
			else{
			this.p_Button.b_Title.text = en_APDHMIDM;
			}
		}
		
		b_Lang();

I am differentiating between two languages for a button label to display. This is the code I have been using all along with Zero issues:

this.p_Button.addEventListener("click", APDHMIDM.bind(this));
this.p_Button.b_Title.text = en_APDHMIDM;

So, if property 'b_Title' is defined there, why isn't it in a simple else if function? 

Ideas, anyone? Thanks. 

[resdesign · Accepted solution]

I think this is a problem with scope.

I would use 

var _this = this

and then use

function b_Lang(){
			if( IsRussia == 1){
			_this.p_Button.b_Title.text = ru_APDHMIDM;
			}
			else{
			_this.p_Button.b_Title.text = en_APDHMIDM;
			}
		}
		
		b_Lang();

[jeffery wright]

These are the sort of things that completely baffle people like me, it does my head in. 

Why var _this = this when you could simply use this in the first place, as I did? 

How did that change any scope when this = the same things as var _this = this?

The value for _this is this, which is what I used in the first place, what does making it the value of a variable do exactly? And how would anyone know to to that? It's black magic. 

Thank you, your suggestion is the solution, I appreciate it.