callback after jQuery.trigger() function

Question

i have got a little problem here. I have to trigger an event which contains $.post() to load a form and assign it to a DOM. After this is done, i have edit the fields of the form.

I tried:

$.when(function(){
    $('#type_rank_field').trigger('change'); //calls the $.post() to load the form
})
 .done(function(){
    $('#quest_'+questions[i].split('|')[1]).children('option[value="'+questions[i].split('|')[0]+'"]').attr('selected',true);
});

Unfortunately this doesnt work and if i leave it just like that:

$('#type_rank_field').trigger('change');
$('#quest_'+questions[i].split('|')[1]).children('option[value="'+questions[i].split('|')[0]+'"]').attr('selected',true);

The change even looks like this:

        $('#type_rank_field').live('change',function(){
        var id = $(this).children('option:selected').attr('id');
        var id_edited = get_id_from_id(id);
        $.post('ajax/load_questions_of_rank.ajax.php',{id: id_edited},function(data){
            //alert(data);
            $('#rank_fields').html(data);
        });
    });

Then the form editation is executed before the form is properly loaded and attached to DOM. This might be a stupid question for JavaScript guys, but i am mainly a PHP guy so dont be cruel :-)

Thanks

Solution 1

Can separate out your change handler code? Something like this:

$('#type_rank_field').on('change',function(){
    handleChange($(this));
});

function handleChange(elem, callback) {
    var id = elem.children('option:selected').attr('id');
    var id_edited = get_id_from_id(id);
    $.post('ajax/load_questions_of_rank.ajax.php',{id: id_edited},function(data){
        //alert(data);
        $('#rank_fields').html(data);
        if (typeof callback === "function") {
            callback(data);
        }
    });
};

Then instead of triggering the change you can just call handleChange passing a callback to execute when the AJAX call is complete:

handleChange($("#type_rank_field"), function(data) {
    $('#quest_'+questions[i].split('|')[1])
        .children('option[value="'+questions[i].split('|')[0]+'"]')
        .attr('selected',true);
});

Solution 2

Return the promise object from your event handler:

$(document).on('change','#type_rank_field',function(){
    var id = $(this).children('option:selected').attr('id');
    var id_edited = get_id_from_id(id);
    return $.post('ajax/load_questions_of_rank.ajax.php',{id: id_edited},function(data){
        //alert(data);
        $('#rank_fields').html(data);
    });
});

and then use triggerHandler() instead.

var promise = $('#type_rank_field').triggerHandler('change');
promise && promise.done(function(){
    // do stuff
});

Here's a simple example showing the functionality being used: http://jsfiddle.net/WQPXt/

Solution 3

I think we have to add callback after posted

$('#type_rank_field').on('change', function(ev, cb){
    var id = $(this).children('option:selected').attr('id');
    var id_edited = get_id_from_id(id);
    $.post('ajax/load_questions_of_rank.ajax.php',{id: id_edited},function(data){
        //alert(data);
        $('#rank_fields').html(data);
        // add after callback to make sure that html is inserted
        if(typeof cb == "function"){
           cb.apply($(this)) // this apply with the jq object context or another context u want
        }
 });

the trigger change will look like this

$('#type_rank_field').trigger('change', [function(){
  $('#quest_'+questions[i].split('|')[1]).children('option[value="'+questions[i].split('|')[0]+'"]').attr('selected',true);
}]);

Comments

[user1377911]

Thanks for your comment Roy. I will rewrite the .live() function to .on() but i think that doesnt help me with my problem. Is it understandable or should i just describe the problem more deep?

[user1377911]

This actually looks like a good idea! I will try it and I will let you know if the problem is solved or not :)

[ROY Finley]

@FelixKling Was try to figure out problem, but user never answered my question form above. Where does get_id_from_id come from? But looks like Matt has it all figured out.

[Felix Kling]

Wow... is this documented?

[Kevin B]

Yes, it is documented, the last bullet in first section. api.jquery.com/triggerHandler

[BLSully]

@MattBurland: I only pointed that out as I use this exact pattern sometimes and I've shot myself in the foot before :D. If JS has taught me anything, it's don't rely on type coercion

[Felix Kling]

Cool. A bit fragile (depends on the order of event handlers), but interesting.

[ROY Finley]

Okay Kevin B puts out an answer using the exact depreciated function live() and gets to upvotes. I place an answer that is telling you not to use this function as it could be part of your problem and I get downvoted. How does that work..... -1

[Kevin B]

That could be fixed with a namespace in 1.9+, though previous versions handled namespaces inconsistently.

[Kevin B]

the use of .live has nothing to do with this question.

[Felix Kling]

@ROY: You are correct, .live should not be used anymore, but not every correct fact answers every question. Your answer does not solve the problem. It's ok as a comment but not as an answer.

[ROY Finley]

So it is okay to give answers using depreciated and removed code as long as it works........ Not good form.

[Kevin B]

How do you know he's not using jQuery 1.3.2? if he mentioned that he was using 1.7+ or was using a method implemented in 1.7+ i'd agree with changing that portion of the code in the answer. All we know is he is atleast using 1.5 due to the deferred usage.

[ROY Finley]

Jquery Says : Users of older versions of jQuery should use .delegate() in preference to .live()..... :)

[user1377911]

This looks ok, but doesnt work :-( I am using 1.8.2. it doesnt even load the form.