George Hess George Hess - 6 months ago 49
Javascript Question

Preserve 'this' reference in javascript prototype event handler

What is the correct way to preserve a

this
javascript reference in an event handler stored inside the object's prototype? I'd like to stay away from creating temp vars like '_this' or 'that' and I can't use a framework like jQuery. I saw a lot of people talk about using a 'bind' function but was unsure of how to implement it in my given scenario.

var Example = function(foo,bar){
this.foo = foo;
this.bar = bar;
};
Example.prototype.SetEvent = function(){
this.bar.onclick = this.ClickEvent;
};
Example.prototype.ClickEvent = function(){
console.log(this.foo); // logs undefined because 'this' is really 'this.bar'
};

Answer

I find bind() being the cleanest solution so far:

this.bar.onclick = this.ClickEvent.bind(this);

BTW the other this is called that by convention very often.

Comments