Compile error when extending a class in typescript

Question

I saw this question which is similar :

Cross referencing with extended classes in TypeScipt

though i couldnt figure out what was wrong still. My problem is that i have a class gameobject that i want to extend but as long as the sprite class that entends gameobject exists i get an error

module Game {
export class GameObject {
    x = 0;
    y = 0;
    W = 0;
    H = 0;
    img = new Image();
    scale = 0;

    constructor(img, x, y, w, h, scale?) {
        this.img = img;
        this.x = x || 0;
        this.y = y || 0;
        this.W = w;
        this.H = h;
        this.scale = scale || 1;
    }
    update() {

    }
    render(context, x, y) {
        context.drawImage(this.img, this.x, this.y, this.W, this.H, x, y, this.W * this.scale, this.H * this.scale);
    }
}
}

.

module Game {
export class Sprite extends GameObject {

}
}

I get the following error:

Uncaught TypeError: Cannot read property 'prototype' of undefined

Uncaught TypeError: undefined is not a function

According to the post at the top, it seems like i have a circular dependency and it it calling the sprite class first for some reason?

Thanks in advance.

typescript 0.9.5, I have no idea what is causing this because even if i dont call the classes above, as long as they are in the project it gives that error. — Shadow
– Shadow, Commented Feb 15, 2014 at 6:09

Simon B.Robert · Accepted Answer · 2016-02-16 16:26:45Z

12

I found the error, apparently you cannot extend files normally when you are outputting the typescript code to one javascript file so you have to use ///reference like this:

///<reference path='gameobject.ts' />
module Game {
    export class Sprite extends GameObject {
    }
}

Post about it:

https://typescript.codeplex.com/workitem/1590

edited Feb 16, 2016 at 16:26

Simon B.Robert

31.8k4 gold badges18 silver badges25 bronze badges

answered Feb 15, 2014 at 14:26

Shadow

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1 Comment

basarat Over a year ago

Yes, that is one of the code organization patterns available to you. The other is amd for the browser : youtube.com/watch?v=KDrWLMUY0R0&hd=1

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