How can I add a prototype function to an event listener in the initialization function?

Question

I'm not sure exactly how to phrase my question, so let me present an example:

function foo() {
  window.addEventListener("keydown", function(event) {
        bar(event.keycode);
}

foo.prototype.bar = function (keycode) {
//code
}

I've tried using this.bar(), but that results in using the window as this. Is there a way to do this, or will I have to call another initialize method manually?

Answer 1

Bind this.bar to this before you pass it.

function foo() {
    window.addEventListener("keydown", this.bar.bind(this), false);
}


foo.prototype.bar = function (event) {
    console.log(event.keyCode);
}

demo http://jsfiddle.net/2tee4/