(FIXED) Method called by mousedown event can't call a different object method

[InfinitySamurai]

Hi guys,

I'm trying to create a class/object that handles all the logic and input for a sprite in my game. When I call a method from the `sprite.on` method, it calls it fine, but it is then unable to call another method inside the same object, it can't find it.

I'm not really sure what I'm doing wrong, can anyone shed some light for me from the code below?

The click event should call the `onClick` method, which it does. Then, when it tried to call the `changeSpeed` method, it gives me the error `TypeError: this.changeSpeed is not a function`

function Spinner(start_speed, decay, max_speed, sprite){
	this.speed = start_speed;
	this.decay = decay;
	this.max_speed = max_speed;
        this.sprite = sprite;
	this.angle = 0;
        this.click_strength = 0.1;


    this.update = function(delta){
        this.changeSpeed(-this.decay*delta);
        this.angle += this.speed;
        this.sprite.rotation += spinner.speed * delta;
    };

    this.changeSpeed = function(amount){
        this.speed += amount;

        if(this.speed > this.max_speed){
            this.speed = this.max_speed;
        }
        else if(this.speed < 0){
            this.speed = 0;
        }
    };

    this.onClick = function(){
        this.changeSpeed(this.click_strength);
        console.log("spinner got clicked");
    };

    this.sprite.on('mousedown', this.onClick);
};

Error traceback:

Spinner/this.onClick http://127.0.0.1:8080/src/spinner.js:28:9
	[3]</o.prototype.emit https://cdnjs.cloudflare.com/ajax/libs/pixi.js/4.5.2/pixi.min.js:8:9704
	[156]</T</e.prototype.dispatchEvent https://cdnjs.cloudflare.com/ajax/libs/pixi.js/4.5.2/pixi.min.js:19:5168
	[156]</T</e.prototype.processPointerDown https://cdnjs.cloudflare.com/ajax/libs/pixi.js/4.5.2/pixi.min.js:19:7256
	bound  self-hosted:917:17
	[156]</T</e.prototype.processInteractive https://cdnjs.cloudflare.com/ajax/libs/pixi.js/4.5.2/pixi.min.js:19:6184
	[156]</T</e.prototype.processInteractive https://cdnjs.cloudflare.com/ajax/libs/pixi.js/4.5.2/pixi.min.js:19:5846
	[156]</T</e.prototype.onPointerDown https://cdnjs.cloudflare.com/ajax/libs/pixi.js/4.5.2/pixi.min.js:19:6567
	bound  self-hosted:913:17

I hope that's enough info, let me know if I've breached any conduct and I look forward to your help!

Cheers.

[InfinitySamurai]

I'm guessing that this has something to do with the `onClick` function no longer having any reference to what object it is a part of after the event has been fired. In the click example, the onClick function refers directly to a global variable which is not particularly viable in a larger solution. Is there a way I can pass the object along with the event?

[themoonrat]

You need to pass in the context to use in the third parameter for event listeners.

this.sprite.on('mousedown', this.onClick, this);

[InfinitySamurai]

Thank you so much! I thought it would be something like this.