Develop Reference

jQuery callbacks cumulation

I'm building a simple jQuery plugin called magicForm (How ridiculous is this?). Now face to a problem that I think I'm not figuring out properly.
My plugin is supposed to be applied on a container element, that will show each of its inputs one by one as user fills them. That's not the exact purpose of my problem.
Each time I initialize the container, I declare an event click callback. Let me show an example.
(function($){
var methods = {
init: function(options){
return this.each(function(){
var form, inputs;
var settings = {
debug: false
};
settings = $.extend(settings, options);
form = $(this);
$('a.submit', form).on('click', function(event){
if (settings.submitCallback) {
settings.submitCallback.call(form, inputs);
}
return false;
});
});
},
reset: function() {
}
}
$.fn.magicForm = function(method) {
if ( methods[method] ) {
return methods[ method ].apply( this, Array.prototype.slice.call( arguments, 1 ));
} else if ( typeof method === 'object' || ! method ) {
return methods.init.apply( this, arguments );
} else {
$.error( 'Method ' + method + ' does not exist.' );
}
};
})($);
I'm focusing on a specific part of this code :
$('a.submit', form).on('click', function(event){
if (settings.submitCallback) {
settings.submitCallback.call(form, inputs);
}
return false;
});
Because each time the init method is called, that poor callback is registered.
I was experiencing this painfully, when I invoked my plugin on an element nested in a twitter bootstrap 'tab', nested itself in a bootstrap modal :
I was calling init each time the event 'shown' of my bootstrap modal was triggered.
So, this is how I fixed it in my init method :
// Prevent callback cumulation
if (!$(this).data('form_initialized')) {
$('a.submit', form).on('click', function(event){
if (settings.submitCallback) {
settings.submitCallback.call(form, inputs);
}
return false;
});
$(this).data('form_initialized', true);
}
And I'm far from feeling sure about this.
Thank your for your time !

Many jquery plugins use data to know if their plugins were initialized. Most often, they use the name of their own plugin as a part (or in whole) as the data. For example:
$(this).data('magicForm')
So your approach of using that to signal is not a bad one.
However, you have two other options:
1) Pull the event handler out so the handler is a single instance. Above your methods, do var fnOnSubmit = function() { ... } Then you can simply ensure proper binding by calling $('a.submit', form).unbind('click', fnOnSubmit) before rebinding it the way you are already doing it.
2) Another option is to use event namespaces.
$('a.submit', form).unbind('click.magicForm'); then rebinding it with .on('click.magicForm') This namespace approach ensures that when you unbind it only unbinds in the context of your namespace magicForm, thus leaving all other click events (e.g. from other plugins) intact.
I hope this helps.

You could first explicitely remove the click-handler:
$('a.submit', form).off('click').on('click', function(event){ ... })
However, I would suggest you use event namespacing to prevent all click handlers (even those perhaps set by code not your own) from being removed:
$('a.submit', form).off('click.magicForm').on('click.magicForm', function(event){ ... })

Event object eaten by jQuery animation callback

I have a problem with event object passed to the function in drop event. In my code, div#dropArea has it's drop event handled by firstDrop function which does some animations and then calls the proper function dropFromDesktop which handles the e.dataTransfer.files object. I need this approach in two separate functions because the latter is also used further by some other divs in the HTML document (no need to duplicate the code). First one is used only once, to hide some 'welcome' texts.
Generally, this mechanism lets you drag files from desktop and drop them into an area on my website.
Here's, how it looks (in a shortcut):
function firstDrop(ev) {
var $this = $(this);
//when I call the function here, it passes the event with files inside it
//dropFromDesktop.call($this, ev);
$this.children('.welcomeText').animate({
opacity: '0',
height: '0'
}, 700, function() {
$('#raw .menu').first().slideDown('fast', function() {
//when I call the function here, it passes the event, but 'files' object is empty
dropFromDesktop.call($this, ev);
});
});
}
function dropFromDesktop(ev) {
var files = ev.originalEvent.dataTransfer.files;
(...) //handling the files
}
$('#dropArea').one('drop', firstDrop);
$('some_other_div').on('drop', dropFromDesktop);
The problem is somewhere in jQuery.animation's callback - when I call my function inside it, the event object is passed correctly, but files object from dataTransfer is empty!
Whole script is put inside $(document).ready(function() { ... }); so the order of function declarations doesn't matter, I guess.

I suspect your problem is related with the lifetime of the Event object. Unfortunately, I have no clue about the cause of it. But, there is a way to workaround it that I can think of and it is keeping a reference to Event.dataTransfer.files instead.
var handleFileList = function(fn) {
return function(evt) {
evt.preventDefault();
return fn.call(this, evt.originalEvent.dataTransfer.files);
};
};
var firstDrop = function(fileList) { ... }
var dropFromDesktop = function(fileList) { ... }
$('#dropArea').one('drop', handleFileList(firstDrop));
$('some_other_div').on('drop', handleFileList(dropFromDesktop));​

jQuery Plugin On Event Return True/False

I'm creating a plugin that replaces alerts/confirms for a project and I was curious if there was a way to make it like a real confirm where you can do:
if(confirm('Yes or no?')){alert('You agreed!');}
Right now I could do with a call back using this syntax:
$.alert('yes or no',{type:'confirm'});
But i want to be able to do:
if($.alert('yes or no',{type:'confirm'})){/*some action on true*/}
Here is what I have so far and look for the all CAPS comments in the click event (remember, this is still in development, so the HTML and stuff is still a little icky):
(function($) {
$.alert = function(message,options) {
defaults = {
type:'alert',
callback:function(){}
}
options = $.extend({},defaults,options);
if(options.type == 'confirm'){
$('<div style="display:none" class="alerthiddenoverlay"></div><div style="display:none" class="customalertbox"><div><img src="http://cdn.iconfinder.net/data/icons/basicset/tick_48.png"><p>'+message+'</p><br class="clear"><span><a class="cancel" href="#cancel">Cancel</a><a class="ok" href="#ok">OK</a></span><br class="clear"></div></div>').prependTo('body');
}
else{
$('<div style="display:none" class="alerthiddenoverlay"></div><div style="display:none" class="customalertbox"><div><img src="http://cdn.iconfinder.net/data/icons/basicset/warning_48.png"><p>'+message+'</p><br class="clear"><span><a class="ok" href="#ok">OK</a></span><br class="clear"></div></div>').prependTo('body');
}
$alertboxclass=$('.customalertbox');
$alerthiddenoverlay=$('.alerthiddenoverlay');
$alertboxclass.find('a').click(function(event){
event.preventDefault();
var the_return = false;
if($(this).attr('href') == '#ok'){
var the_return = true;
}
$alertboxclass.fadeOut(250,function(){$alerthiddenoverlay.delay(250).fadeOut(250,function(){$(this).remove();options.callback.call(this,the_return);});$(this).remove()});
});
$alertboxclass.css({
top:$(window).height()/2-$alertboxclass.height()/2,
left:$(window).width()/2-$alertboxclass.width()/2
});
$alerthiddenoverlay.css({height:$(window).height()+'px',width:'100%',position:'fixed',zIndex:'9998'}).fadeIn(250,function(){$alertboxclass.delay(250).fadeIn()});
}
})(jQuery);

I think passing a callback method in as a parameter to the $.alert function is going to be the easiest option. If that's a deal-breaker though, I might look at the .queue() method for chaining the events.
http://api.jquery.com/queue/

I saw a nice confirm() overwrite to a modal window as an example of jqModal
Here is the code sample. I'm sure you can adapt it to your need...
/* Overriding Javascript's Confirm Dialog */
// NOTE; A callback must be passed. It is executed on "cotinue".
// This differs from the standard confirm() function, which returns
// only true or false!
// If the callback is a string, it will be considered a "URL", and
// followed.
// If the callback is a function, it will be executed.
function confirm(msg,callback) {
$('#confirm')
.jqmShow()
.find('p.jqmConfirmMsg')
.html(msg)
.end()
.find(':submit:visible')
.click(function(){
if(this.value == 'yes')
(typeof callback == 'string') ?
window.location.href = callback :
callback();
$('#confirm').jqmHide();
});
}
$().ready(function() {
$('#confirm').jqm({overlay: 88, modal: true, trigger: false});
// trigger a confirm whenever links of class alert are pressed.
$('a.confirm').click(function() {
confirm('About to visit: '+this.href+' !',this.href);
return false;
});
});

Get text from field on keyup, but with delay for further typing

I have a form which is submitted remotely when the various elements change. On a search field in particular I'm using a keyup to detect when the text in the field changes. The problem with this is that when someone types "chicken" then the form is submitted seven times, with only the last one counting.
What would be better is something like this
keyup detected - start waiting (for one second)
another keyup detected - restart waiting time
waiting finishes - get value and submit form
before I go off and code my own version of this (I'm really a backend guy with only a little js, I use jQuery for everything), is there already an existing solution to this? It seems like it would be a common requirement. A jQuery plugin maybe? If not, what's the simplest and best way to code this?
UPDATE - current code added for Dan (below)
Dan - this may be relevant. One of the jQuery plugins I'm using on the page (tablesorter) requires this file - "tablesorter/jquery-latest.js", which, if included, leads to the same error with your code as before:
jQuery("input#search").data("timeout", null) is undefined
http‍://192.168.0.234/javascripts/main.js?1264084467
Line 11
Maybe there's some sort of conflict between different jQuery definitions? (or something)
$(document).ready(function() {
//initiate the shadowbox player
// Shadowbox.init({
// players: ['html', 'iframe']
// });
});
jQuery(function(){
jQuery('input#search')
.data('timeout', null)
.keyup(function(){
jQuery(this).data('timeout', setTimeout(function(){
var mytext = jQuery('input#search').val();
submitQuizForm();
jQuery('input#search').next().html(mytext);
}, 2000)
)
.keydown(function(){
clearTimeout(jQuery(this).data('timeout'));
});
});
});
function submitQuizForm(){
form = jQuery("#searchQuizzes");
jQuery.ajax({
async:true,
data:jQuery.param(form.serializeArray()),
dataType:'script',
type:'get',
url:'/millionaire/millionaire_quizzes',
success: function(msg){
// $("#chooseQuizMainTable").trigger("update");
}
});
return true;
}

Sorry i haven't tested this and it's a bit off the top of my head, but something along these lines should hopefully do the trick. Change the 2000 to however many milliseconds you need between server posts
<input type="text" id="mytextbox" style="border: 1px solid" />
<span></span>
<script language="javascript" type="text/javascript">
jQuery(function(){
jQuery('#mytextbox')
.data('timeout', null)
.keyup(function(){
clearTimeout(jQuery(this).data('timeout'));
jQuery(this).data('timeout', setTimeout(submitQuizForm, 2000));
});
});
</script>

Here's your fancy jquery extension:
(function($){
$.widget("ui.onDelayedKeyup", {
_init : function() {
var self = this;
$(this.element).keyup(function() {
if(typeof(window['inputTimeout']) != "undefined"){
window.clearTimeout(inputTimeout);
}
var handler = self.options.handler;
window['inputTimeout'] = window.setTimeout(function() {
handler.call(self.element) }, self.options.delay);
});
},
options: {
handler: $.noop(),
delay: 500
}
});
})(jQuery);
Use it like so:
$("input.filterField").onDelayedKeyup({
handler: function() {
if ($.trim($(this).val()).length > 0) {
//reload my data store using the filter string.
}
}
});
Does a half-second delay by default.

As an update, i ended up with this which seems to work well:
function afterDelayedKeyup(selector, action, delay){
jQuery(selector).keyup(function(){
if(typeof(window['inputTimeout']) != "undefined"){
clearTimeout(inputTimeout);
}
inputTimeout = setTimeout(action, delay);
});
}
I then call this from the page in question's document.ready block with
afterDelayedKeyup('input#search',"submitQuizForm()",500)
What would be nice would be to make a new jquery event which uses this logic, eg .delayedKeyup to go alongside .keyup, so i could just say something like this for an individual page's document.ready block.
jQuery('input#search').delayedKeyup(function(){
submitQuizForm();
});
But, i don't know how to customise jquery in this way. That's a nice homework task though.

Nice job, Max, that was very helpful to me! I've made a slight improvement to your function by making it more general:
function afterDelayedEvent(eventtype, selector, action, delay) {
$(selector).bind(eventtype, function() {
if (typeof(window['inputTimeout']) != "undefined") {
clearTimeout(inputTimeout);
}
inputTimeout = setTimeout(action, delay);
});
}
This way you can use it for any type of event, although keyup is probably the most useful here.

I know this is old, but it was one of the first results when I was searching for how to do something like this so I though I would share my solution. I used a combination of the provided answers to get what I needed out of it.
I wanted a custom event that worked just like the existing jQuery events, and it needed to work with keypress + delete, backspace and enter.
Here's my jQuery plugin:
$.fn.typePause = function (dataObject, eventFunc)
{
if(typeof dataObject === 'function')
{
eventFunc = dataObject;
dataObject = {};
}
if(typeof dataObject.milliseconds === 'undefined')
dataObject.milliseconds = 500;
$(this).data('timeout', null)
.keypress(dataObject, function(e)
{
clearTimeout($(this).data('timeout'));
$(this).data('timeout', setTimeout($.proxy(eventFunc, this, e), dataObject.milliseconds));
})
.keyup(dataObject, function(e)
{
var code = (e.keyCode ? e.keyCode : e.which);
if(code == 8 || code == 46 || code == 13)
$(this).triggerHandler('keypress',dataObject);
});
}
I used $.proxy() to preserve the context in the event, though there could be a better way to do this, performance-wise.
To use this plugin, just do:
$('#myElement').typePause(function(e){ /* do stuff */ });
or
$('#myElement').typePause({milliseconds: 500, [other data to pass to event]},function(e){ /* do stuff */ });

How to — callback functions

I have a big problem writing a small piece of code using JS/jQuery (don't know which of these is causing the problem). Anyhow, here we go:
$('#themePicker').unbind().click(function() {
var t = $(this);
modalwindow2(t, function() {
console.log(1);
}, function(w) {
console.log(w);
});
return false;
});
and the function itself:
function modalwindow2(w, callbackOnSHow, callbackOnHide) {
if (typeof(callbackOnSHow) == 'function') {
callbackOnSHow.call();
}
// do some stuff //
$('form').submit(function() {
ajaxSubmit(function(data) {
if (typeof(callbackOnHide) == 'function') {
console.log('---------------');
console.log(data);
console.log('---------------');
callbackOnHide.call(data);
}
});
return false
});
}
The function is called modalwindow2 and I want to call a function when the modal is shown and another function when the modal will be hidden.
The first is not a problem.
The second… Well… Let's just say it's a problem. Why?
I want a parameter sent to the second function. The paramenter is an ajax response, similar to other jQuery stuff (ajax action, sortable, etc).
I hope I made myself clear enough.
Thanks!
Edit:
I'm using jQuery 1.1.2 (or 1.1.3) and upgrading or using jQuery UI is NOT a solution. I have some dependencies (interface is one of them) and i don't have enough time (nor motivation) to upgrade to 1.3 & UI 1.7.

I noticed that you have a typo on .submit:
$('form').submti(function(){
Was that just an entry error to SO?
EDIT:
Ok, so after looking at your code and doing a short test, I've come up with this (pardon the pun):
function modalwindow2(w, callbackOnShow, callbackOnHide) {
if(typeof callbackOnShow == 'function') {
callbackOnShow.call();
}
$('form').submit(function() {
if(typeof callbackOnHide == 'function') {
callbackOnHide.call(this, "second");
}
});
}
$(document).ready(function (){
$('#themePicker').click(function(){
var t=$(this);
modalwindow2(t, function() { alert("first"); }, function(x) { alert(x); });
return false;
});
});
It looks like you may have just been missing the "this" in your call() statement. Try using callbackOnHide.call(this, data);
Let me know if that works any better!

I understand what you are trying to do, but you will need to store the newly created window so that you can access it on the close callback function.
You might want to look at jQuery UI Dialog. It provides some really basic functionality for dialog windows (modal and otherwise) and handles some of the callback implementation.