Newb question regarding functions and Scope

[Lihinel]

Okay, it just hit me, it should have been this.drawName(); so it was a Syntax error on my part, problem is no tutorial I read said how to use a method/function, only how to define it.


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Just started out with JS and am a bit uncertain why the following code works, but my attempt at changing and modularising it lead to some problems. First the original:

Scene_Title.prototype.drawGameTitle = function() {

// Background
var bitmap = ImageManager.loadTitle1('TitleBG');
var bg = new Sprite(bitmap);
this._bg = bg;
this.addChild(bg);

...

// Title Name
var bitmap = ImageManager.loadTitle1('TitleName');
var titleName = new Sprite(bitmap);
this._titleName = titleName;
this._bg.addChild(titleName);
}

I wanted to change it so that all my sprites are added in their own sub-methods, or in this case functions:

...


// Title Name
Scene_Title.prototype.drawName();
}

Scene_Title.prototype.drawName = function() {
var bitmap = ImageManager.loadTitle1('TitleName');
var titleName = new Sprite(bitmap);
this._titleName = titleName;
this._bg.addChild(titleName);
}

Appearently this._bg is undefined in the new function, so what am I doing wrong? Is it a simple Syntax error or have I missed something deeper? (I am most familiar with Ruby where this kind of thing should have worked)

 

[TheoAllen]

You don't do this

Scene_Title.prototype.drawName();

You do this

this.drawName();

What you're calling is a prototype function.

 

[Poryg]

problem is no tutorial I read said how to use a method/function, only how to define it.

Go through some c++ tutorials on object oriented programming. The basics should be enough.

 

[TheoAllen]

Missed that point. But here's the tutorial https://developer.mozilla.org/en-US/docs/Web/JavaScript/Inheritance_and_the_prototype_chain

 

[MushroomCake28]

Theo nailed it: use

this.drawName();

and not the prototype.