this keyword and closures

[Jeff]

I have a question about closures. Take for example the addBehavior
method below from the Low Pro library

Event.addBehavi or = function(rules) {
var ab = this.addBehavio r;
Object.extend(a b.rules, rules);

if (!ab.responderA pplied) {
Ajax.Responders .register({
onComplete : function() {
if (Event.addBehav ior.reassignAft erAjax)
setTimeout(func tion() { ab.reload() }, 10);
}
});
ab.responderApp lied = true;
}

if (ab.autoTrigger ) {
this.onReady(ab .load.bind(ab, rules));
}

};

var ab is initialized to this.addBehavio r. It is then extended using
Object.extend(a b.rules.rules). However, in the Ajax.Responders
onComplete function, addBehavior is referenced using
Event.addBehavi or.reassignAfte rAjax instead of ab.reassignAfte rAjax.
Then, immediately after, ab.reload is referenced. Why is this? Instead
of ab.rules, why wasn't
Object.extend(E vent.addBehavio r.rules, rules), or even
Object.extend(t his.addBehavior .rules, rules)? Does it have to do with
closures?

[Joost Diepenmaat]

Re: this keyword and closures

Jeff <jknight12882@g mail.comwrites:

I have a question about closures. Take for example the addBehavior
method below from the Low Pro library

Never heard of that library, but ok.

Event.addBehavi or = function(rules) {
var ab = this.addBehavio r;
Object.extend(a b.rules, rules);
>
if (!ab.responderA pplied) {
Ajax.Responders .register({
onComplete : function() {
if (Event.addBehav ior.reassignAft erAjax)
setTimeout(func tion() { ab.reload() }, 10);
}
});
ab.responderApp lied = true;
}
>
if (ab.autoTrigger ) {
this.onReady(ab .load.bind(ab, rules));
}
>
};
>
var ab is initialized to this.addBehavio r. It is then extended using
Object.extend(a b.rules.rules).

yes.

However, in the Ajax.Responders onComplete function, addBehavior is
referenced using Event.addBehavi or.reassignAfte rAjax instead of
ab.reassignAfte rAjax.

It's not clear from the code that Event.addBehavi our.reassignAft erAjax
=== ab.reassignAfte rAjax, though it probably is.

Then, immediately after, ab.reload is referenced. Why is this? Instead
of ab.rules, why wasn't
Object.extend(E vent.addBehavio r.rules, rules), or even

because it's shorter?

Object.extend(t his.addBehavior .rules, rules)? Does it have to do with
closures?

since you can't close over this, yes, it has to do with closures. this
is NOT a variable.

--
Joost Diepenmaat | blog: http://joost.zeekat.nl/ | work: http://zeekat.nl/