Wonderful!
Thanks.
On Sep 20, 12:16 pm, Michael Geary <m...@mg.to> wrote:
> Ah, I did misread the problem. Now I follow you, thanks for the
> clarification.
>
> There is indeed a better and simpler way to do this, which works with
> *any*kind of asynchronous callback. You don't need to rely on having a
> specific
> object returned that you can stuff data into. Simply use a closure.
>
> For example:
>
> function jsonRequest( url, myVariable ) {
> $.getJSON( url, function( data ) {
> // here you have access to data and myVariable
> });
>
> }
>
> jsonRequest( 'test1.php', 'hello world' );
> jsonRequest( 'test2.php', 'goodbye cruel world' );
> jsonRequest( 'test3.php', 'off to join the circus' );
>
> Each of those jsonRequest() calls has its own private 'myVariable' - no
> globals needed.
>
> Even for ordinary XHR, I think this is a much cleaner way to pass data into
> the callback than messing with the XHR object, and the nice thing is you can
> always use the same technique.
>
> It's no different from how you might use a closure with setTimeout or any
> other async function:
>
> function delayedAlert( time, message ) {
> setTimeout( function() {
> alert( message );
> }, time );
>
> }
>
> delayedAlert( 1000, 'one second' );
> delayedAlert( 10000, 'ten seconds' );
>
> -Mike
>
> On Sat, Sep 19, 2009 at 5:12 PM, Blixa <shulgisnotmyem...@gmail.com> wrote:
>
> > Hi Mike,
>
> > I think you might have misread my post and the code attached.
>
> > I am quite aware of the fact that the callback function only runs upon
> > a successful completion of the request and is run asynchronously. If
> > you look at the code i've written you'll see that i am in fact
> > _counting_ on that since i am declaring variable_from_caller in the
> > line after the callback code as i know this code will be run before
> > the callback code (which contains a reference to
> > variable_from_caller).
>
> > My question, again, was in regards to passing data TO the callback
> > function and not FROM the callback function. In my scenario i have to
> > consider the possibility of multiple getJSONs called and so multiple
> > callbacks running side by side so that i cannot use global variables
> > to store this data, which is specific to each of the callback. The way
> > i described here uses the actual XMLHttpRequest object (by assigning
> > $.getJSON to the variable new_json) and only works if i modify the
> > jQuery code (like i mentioned in my original post).
> > Is there another way of passing data TO the callback function that is
> > not global, other than the way i've done it?
> > Shouldn't getJSON _ALWAYS_ return an XMLHttpRequest object, as the
> > documentation states?
>
> > On Sep 20, 12:17 am, Michael Geary <m...@mg.to> wrote:
> > > getJSON, like all Ajax and Ajax-style calls, is *asynchronous*. That's
> > what
> > > the A in Ajax stands for.
>
> > > Instead of trying to use a return value, you need to use the
> > > getJSONcallback function (which you're already providing) to do
> > > whatever you want
> > > with the data.
>
> > > So your code might look something like:
>
> > > $.getJSON( url, function( data ) {
> > > // do stuff with data here, such as:
> > > callSomeOtherFunction( data );
>
> > > });
>
> > > In that callback function, you can store the data anywhere you want. You
> > can
> > > call other functions. You can do anything you need to.
>
> > > What you *can't* do is try to use the data immediately after
> > > getJSONreturns. At that point, the data has not yet been downloaded.
> > > You have to
> > > use the callback function and call any other functions you need from
> > there.
>
> > > -Mike
>
> > > On Sat, Sep 19, 2009 at 1:16 PM, Blixa <shulgisnotmyem...@gmail.com>
> > wrote:
>
> > > > I am using getJSON to get results from a different domain and i wanted
> > > > to get _some_ object back when calling getJSON so that i can insert
> > > > some variables into the callback scope.
> > > > Basically, what i wanted to do was this:
>
> > > > var new_json = $.getJSON(url, function(data) {
> > > > alert
> > > > (this.variable_from_caller);
> > > > });
> > > > new_json.variable_from_caller = 'value';
>
> > > > The problem is that since url is on a different domain, the call to
> > > > getJSON (which end up calling ajax) returns undefined and not an
> > > > object that can be referenced (this is on line 3504 of the
> > > > uncompressed jquery-1.3.2.js).
>
> > > > I've noticed that if i change undefined to s i can reference the
> > > > object from outside and have the variable exist within 'this' inside
> > > > the anonymous callback, although s is not an XMLHttpRequest.
>
> > > > Is this a bug? am i doing something wrong or twisted and there's a
> > > > much easier way of accomplishing this in a way i am not aware of?
