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Answer 1

+3 A:

What about creating an external variable before referencing to 'this' object. For example:

var _this = this;
this.chart.addEventListener('create', function() { _this.fireEvent('created'); }, false)

nandokakimoto 2009-11-26 11:42:34

Yes, this is the normal idiom. The closure variable is often called `that` or `self` (although I don't think the latter's a great idea as `self` has an established — though useless — existing meaning in JavaScript).

bobince 2009-11-26 11:48:31

OK that works. Out of interest is there another way other than setting a variable to this. For example using closure?

Jonnio 2009-11-26 12:12:33

@bobince: I prefer `self`. `self` is exposed by `window` a reference to itself. I'm quite happy to reuse the identifier in other scopes. It seems to me to carry the right meaning and doesn't clash with that it means when `self` happens to be the window either.

AnthonyWJones 2009-11-26 12:17:37

Answer 2

+1 A:

This is the typical approach to this problem:-

(function(self) {
  self.chart.addEventListener('create', function() {self.fireEvent('created');}, false);
})(this);

AnthonyWJones 2009-11-26 12:12:58

I prefer `var self = this;`. Creating a function and then executing it whilst passing `this` as the parameter seems a little overboard - the code is slightly longer too ;-)

Andy E 2009-11-26 12:32:36

@Andy: Yes I often do that too when the code exists in a small execution context. However the above is the standard approach which works in a wider variety of scenarios. The scope of the `self` identifier is limited only to the closure, there is no danger that subsequent code might modify the value contained in it before the event fires. This is not true of the `var self = this;` approach.

AnthonyWJones 2009-11-26 13:13:27

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