How to use keyword this in a mouse wrapper in right context in Javascript?
- by MartyIX
Hi,
I'm trying to write a simple wrapper for mouse behaviour. This is my current code:
function MouseWrapper() {
this.mouseDown = 0;
this.OnMouseDownEvent = null;
this.OnMouseUpEvent = null;
document.body.onmousedown = this.OnMouseDown;
document.body.onmouseup = this.OnMouseUp;
}
MouseWrapper.prototype.Subscribe = function (eventName, fn) {
// Subscribe a function to the event
if (eventName == 'MouseDown') {
this.OnMouseDownEvent = fn;
} else if (eventName == 'MouseUp') {
this.OnMouseUpEvent = fn;
} else {
alert('Subscribe: Unknown event.');
}
}
MouseWrapper.prototype.OnMouseDown = function () {
this.mouseDown = 1;
// Fire event
$.dump(this.OnMouseDownEvent);
if (this.OnMouseDownEvent != null) {
alert('test');
this.OnMouseDownEvent();
}
}
MouseWrapper.prototype.OnMouseUp = function () {
this.mouseDown = 0;
// Fire event
if (this.OnMouseUpEvent != null) {
this.OnMouseUpEvent();
}
}
From what I gathered it seems that in MouseWrapper.prototype.OnMouseUp and MouseWrapper.prototype.OnMouseDown the keyword "this" doesn't mean current instance of MouseWrapper but something else. And it makes sense that it doesn't point to my instance but how to solve the problem?
I want to solve the problem properly I don't want to use something dirty.
My thinking:
* use a singleton pattern (mouse is only one after all)
* pass somehow my instance to OnMouseDown/Up - how?
Thank you for help!
