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I need help using queue()

in Using jQuery • 8 years ago

Folks,

I believe the function I need to use is .queue though am open to alternative suggestions. My attempts to resolve this so far have failed, hence why I am here :)

InitData()

Contains an ajax call and successfully retrieves data via JSON and stores it locally with .data()

I have tested and can confirm the data is read, saved and available.

DrawScreen()

Draws table #sui and dynamically applies cells, buttons, text boxes.

Problem:

I got a chicken/egg sort of thing - the data cannot be displayed if the screen has not completed its draw, and when drawn, it cannot display data that it does not yet have... Sometimes my data is read faster from my local hosted database than drawing the screen (the amount of data at this moment is small, and the database is hosted with apache on the same laptop that has the browser).

I welcome all help! Various attempts prove to be unreliable solutions, including variations of $(document).ready() and $(document).load()

$(document).ready( function()

{

InitData();

DrawScreen();

}

How can I create an event that is executed only when the above two functions have completed? Do I use .queue() or something else? I have made it work by inserting delays, but I think this is a dirty workround...

All help appreciated...

Replies(4)

quozzo

Re: I need help using queue()

8 years ago

Looks like what you need is the deferred object, specifically the when function but depending on how your drawing the table you might need to manually resolve the promise object.

fiprojects

WAS: I need help using queue() instead resolved using $.Callbacks()

8 years ago

I'm down with 'flu :( which is effecting my concentration... I have tried the methods you suggested but I can't get my head around it... I did stumble upon the callbacks object which appears to do exactly what I want to do... I'll have to test it plenty, but for now, my tests using laptop, ipad and playbook have returned the results that I expected after a dozen page loads and empty caches.

I placed something similar to the following inside a $(document).ready( function() {} ); call:

var callbacks=$.Callbacks();

callbacks.add( DrawScreen );

callbacks.add( InitData );

callbacks.fire();

A hint of a delay is thrown during page load but I can accept and understand this as I guess its waiting for the outstanding function to complete. It appears once the callbacks.fire() completes, my app is ready to rumble...

Thanks for the prompt reply/help!

Kevin B

Re: I need help using queue()

8 years ago

Make your initData method return a promise object:

function InitData() {
return $.ajax(...)
}

With that, you can now bind to it's done callback.

<script>
InitData().done(function(){
$(DrawScreen); // run DrawScreen when the DOM is ready and data is available
});
</script>

-- Kevin

fiprojects

Re: I need help using queue()

8 years ago

Thanks Kevin... It is the second or third time you have reached out and helped - I appreciate that...

Until now, I was not clear what a Promise Object was - or put more correctly, I knew and used the functionality of the Promise Object without actually knowing what it was called...

One of the solutions I had put in place was to call the DrawScreen() function in the $.ajaxComplete - but I knew I would eventually find myself with the same problem again... The issue I had using the Promise Object is that as my development will continue and grow with functionality, I will not always have Promise objects to rely on - I will sometimes just have to wait for an event to occur in the DOM... Thus, I think in this case, the Callbacks object (mentioned three or four minutes before your reply) prove to be the better fit for my needs (at least at the moment).

I am grateful though for you pointing my weak head (with a cold/flu) in the direction of the Promise object...

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Re: I need help using queue()

WAS: I need help using queue() instead resolved using $.Callbacks()

Re: I need help using queue()

Re: I need help using queue()

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