Exercise in Callbacks [#bestpractices]

[jiggliemon]

I'm having a hard time wrapping my head around the practice of
Callbacks. Arron rewrote one of my examples using callbacks, and no
matter how much I search for a good description of "How and Why" to
use them, I'm always left empty. So why not take it to the smartest
people in Javascript?

I wrote a little fiddle of two functions that I would like to chain,
But due to the asynchronous nature of "Ajax", my second function is
fired before prior to the first Function's completion.

I realize in the current example. I could simply attache function 2 to
the Asset.images's #onComplete method, but that's going to defeat the
purpose of my little exercise - using callbacks.

Any help in executing a simple "Callback" method, would be awesome.

Thanks dudes!

http://jsfiddle.net/mvmvp/

[Ryan Florence]

I'm not clear about what you're asking.

Callbacks, or events, are simply functions that you can call when stuff happens.

Can you ask a specific question? Your demo looks like you get the gist of it.

[Paul Saukas]

I believe your looking for this . http://jsfiddle.net/SA2kQ/

A callback by my understanding (self taught so be warned) is a function B called on completion of another function A from within Function A . 

Thus the move of afterImagesLoaded(); from the domready to the onComplete of getImages().

[Paul Saukas]

good god that was typed to fast :) correction to basic English .

A callback by my understanding (self taught so be warned) is
 

Function B called on completion of Function A from within Function A . 

[nwhite]

On Fri, Jun 25, 2010 at 11:19 AM, Paul Saukas <araso...@gmail.com> wrote:

good god that was typed to fast :) correction to basic English .

A callback by my understanding (self taught so be warned) is
 

Function B called on completion of Function A from within Function A . 

Whereas Function B is an argument passed to Function A.

Both examples are using callbacks... domready, function(){..} is a callback, all the 'on' functions in Assets.images are callbacks that have been abstracted to an interface. However the way 'afterImagesLoaded' and 'updateProgress' are called are not true callbacks.

http://docs.jquery.com/Types#Callback

[Paul Saukas]

Thanks!  Now I have a better/correct understanding as well :D

[jiggliemon]

http://jsfiddle.net/mvmvp/2/
This is Essentially what I would like to happen.

var Getter = new getImages();

// Check ig get Imates is complete.
//Is get Images complete?
//If so, move on, if not... check back later.
while(Getter.state == false) { wait a second.... then check again }

Now fire afterImagesLoaded();



On Jun 25, 11:48 am, nwhite <changereal...@gmail.com> wrote:

> On Fri, Jun 25, 2010 at 11:19 AM, Paul Saukas <arasoihe...@gmail.com> wrote:
> > good god that was typed to fast :) correction to basic English .
>
> > A callback by my understanding (self taught so be warned) is
>
> > Function B called on completion of Function A from within Function A .
>
> Whereas Function B is an argument passed to Function A.
>
> Both examples are using callbacks... domready, function(){..} is a callback,
> all the 'on' functions in Assets.images are callbacks that have been
> abstracted to an interface. However the way 'afterImagesLoaded' and
> 'updateProgress' are called are not true callbacks.
>
> http://docs.jquery.com/Types#Callback
>
>
>
>
>

> > On Fri, Jun 25, 2010 at 2:17 PM, Paul Saukas <arasoihe...@gmail.com>wrote:
>
> >> I believe your looking for this .http://jsfiddle.net/SA2kQ/

[jiggliemon]

Ok i've come to realize how silly the questions is, and how it's
impossible.
Unless someone has a magical way to pause a particular timeline...

The basis for my thinking was an answer i got from Aaron a while back
regarding a similar timeline issue.
His answer contained callbacks to contain functions that returned what
i was waiting for (that's quite a sentence).

However after a better examination of Aaron's answer proves that it in
no way describes what I was thinking about.

Here's the response that I got a while back that made me think
somewhere in the world of javascript I would be able to work around
they synchronistic/asynchronous issues.
http://paste.mootools.net/f401cfb7c