We Keep Coding

CKEditor - grab content from editor to setup live total word count

I'm trying to access the live content from each instance of CKEditor so I can setup a total word count. Before using CKEditor I would get the textarea's content with .getElementById(), and then I would get the live word count by passing the textarea element into my Countable() function which appends an event listener to the area. Is there a way to grab the live content of a CKEditor instance? I know it's an iframe so I'm not sure if it's possible to grab the live content.
Code I used to use with simple textarea:
var area1 = document.getElementById('textarea1');
Countable.live(area1, function(counter1) {
jQuery("#word_count1").text(counter1.words);
a1_count = counter1.words;
total_count();
});

This depends a lot on your Countable function and it's requirements - it would have helped to seen it and to know it's requirements. You can get the contents of each CKEditor instance in a few different methods, this is one
var contentArray = [];
var i = 0;
for (var instance in CKEDITOR.instances) {
var tmpEditor = CKEDITOR.instances[instance];
contentArray[i] = tmpEditor.getData();
i++;
}
Now the contents are in the contentArray. But form your code it looks like Countable needs an element. I'm unsure as to what kind of element reference it can use, but something like this might get you further:
var editor = CKEDITOR.instances.editor1; // change "editor1" to suit your editor
var element = editor.editable().$; // Get a reference to the body of the instance
Countable.live(element, function(counter1) {
jQuery("#word_count1").text(counter1.words);
a1_count = counter1.words;
total_count();
});
Now of course this only supports one editor instance, but the two examples combined might do the trick. Hopefully you don't use inline instances (it needs some additional work but is doable). Also note that naturally these return the source, not the text.
Also not that you do not want to loop this very quickly, it is very cpu intensive. I recommend a slow loop combined with the the CKEditor change event and maybe some other events that trigger the update. Do not trigger on every change, rather set a timeout to buffer the update trigger (you don't want to do the update when the user is typing).

Is there any function in javascript, to detect a change in document? [duplicate]

This question already has answers here:
Attaching jQuery plugin calls to dynamically loaded elements via jQuery,on()
(3 answers)
Closed 9 years ago.
I have an HTML page, which contains many select boxes, to beautify those boxes I have used "select2", What I have done is:
$(document).ready(function() { $("select").select2(); });
This makes all of the select boxes to get transform like "select2".
But now I am generating the tables on a button click(after the document is ready), therefore the newly generated select boxes doesn't looks like "select2", Please help me if there is any function that detects the change in document?
Something like:
$(document).change(function() { $("select").select2(); });

In at least some browsers (not any current version of IE, though), you can do this, via a MutationObserver (this is the new DOM4 thing, not the old DOM3 mutation events, which you want to stay away from).
But I don't recommend it, just call select2 again after your code that appends the new selects.
Another option is to use a timer: Get a NodeList of all select elements on the page:
var allSelects = document.getElementsByTagName('select');
...and poll checking its length (NodeLists are live, you don't have to re-query):
var lastLength = 0;
setInterval(function() {
if (allSelects.length !== lastLength) {
lastLength = allSelects.length;
// Hook up the new ones here
}
}, 1000); // 1000ms = 1 second
You could put a class on them to keep track of which ones are already done (if select2 doesn't already do that).
But again, you have code adding select elements, just re-trigger there.

You can try something like this:
function checkDocumentChange() {
// Run a simple task to check whether any new "selects" were added
var old_value = checkDocumentChange.num_selects || 0;
var new_value = $("select").length;
if (old_value != new_value) {
$("select:not(.already_done)").select2();
}
checkDocumentChange.num_selects = new_value;
setTimeout(checkDocumentChange, 100);
}
DOM events are not recommended to use since those are deprecated.
Better approach would be, of course, to call .select2() right after you insert select into DOM. So that you will not have to delegate this to some checker or event.

You can try DOMNodeInsertedIntoDocument
$(document).on('DOMNodeInsertedIntoDocument', function() {
}
Or mutation observer

use this id or class
in this code
var id = document.getelementbyid("id for select 1 or 2");
//here the code

Why does renaming an HTML element remove its events?

I've noticed that when I change the ID or name of a form element via JavaScript, the jQuery events that were tied to it are no longer there. I've tried this with Firefox 17 and IE 10. Is this by design? And if so, is there any way to prevent it?
UPDATE: Please check http://jsfiddle.net/qHH7P/2/ for an example.
I'm adding the button to remove the row via jQuery. When I remove the first row, I give the elements in the second row a new name and ID. Then the remove button for that remaining row doesn't fire the event anymore. I need to rename the elements because ASP.NET MVC expects a certain naming convention for the collection of objects when binding. That's why I need to rename them with a "0" instead of "1". I'm doing my rename with
var regexpattern = new RegExp("WorkspaceQuestionSets\\[.+\\]", "g");
$(this).html($(this).html().replace(regexpattern, "WorkspaceQuestionSets[" + index + "]"));
var regexpattern = new RegExp("WorkspaceQuestionSets_.+__", "g");
$(this).html($(this).html().replace(regexpattern, "WorkspaceQuestionSets_" + index + "__"));
I just realized that I'm not even renaming the buttons. So it makes even less sense that the event is gone. But if I comment out the code to rename the elements, the event remains.

You are rewriting the HTML. .html() returns a string, which you then modify and set again. The browser will parse that HTML string and create new DOM elements from it. In this process, your destroying DOM elements and consequently loose the event handlers you bound to them before.
I just realized that I'm not even renaming the buttons. So it makes even less sense that the event is gone.
You are destroying and recreating every single element that is inside this (each row I assume), no matter whether you modified its HTML representation or not.
You have to possibilites to solve this:
Use event delegation: Instead of binding the event handlers directly to the elements, bind them to an ancestor, which will always exist. Read more about event delegation in the .on *[docs] documentation, section Direct and delegated events.
Don't rewrite the HTML. Select the elements whose name attribute you want to modify and modify it. For example:
var name_exp1 = /WorkspaceQuestionSets\[.+\]/g;
var name_exp2 = /WorkspaceQuestionSets_.+__/g;
sourceEle.closest(".table").find(".row.set").each(function(index) {
// Edit the name attribute of all `select` and `input` elements
$(this).find('select, input').prop('name', function(i, name) {
if (name_exp1.test(name)) {
return name.replace(
name_exp1,
"WorkspaceQuestionSets[" + index + "]"
);
}
else if (name_exp2.test(name)) {
return name.replace(
name_exp1,
"WorkspaceQuestionSets_" + index + "__"
);
}
return name;
});
});
In JavaScript, forget the HTML and work with the DOM.

This does not happen to me with plain JavaScript in Chrome 24.
Here's what I typed in the JS console:
document.write("<button id='bb'/>")
//undefined
var bb=document.getElementById('bb')
//undefined
bb
//<button id=​"bb">​</button>​
bb.addEventListener('click',function(){alert('hi');});
//undefined
bb
//<button id=​"bb">​</button>​
bb.id
//"bb"
bb.id="qq"
//"qq"
bb
//<button id=​"qq">​</button>​
document.getElementById("bb")
//null
document.getElementById("qq")
//<button id=​"qq">​</button>​
And importantly clicking the button made the event trigger both before and after the assignment to bb.id.
Also in Firefox 17 I didn't quite see that happening with plain JavaScript. I was on the page: http://start.ubuntu.com/12.04/Google/?sourceid=hp
And in the console here's what I issued:
[19:29:41.261] var bb=document.getElementById('sbtn')
[19:29:41.267] undefined
[19:29:45.501] bb.addEventListener('click',function(){alert('hi')});
[19:29:45.507] undefined
[19:29:48.292] bb.id
[19:29:48.298] "sbtn"
[19:29:59.613] bb.id="sbttttttn"
[19:29:59.619] "sbttttttn"
The alert still occurred after the id was changed.
This must be specific to either IE, which I cannot try, or the way jQuery sets up events or handles ID changes (perhaps invisibly destroying the object?).

how to remove keyup event listeners by javascript

I'm using the Google autocomplete api on a text field to suggest locations as you type.
The main problem I have with this is that Google does not let you limit results to a specific country, it just lets you bias results to area bounds which is kind of useless.
So seaching for term "ru" will give you Russia in suggestions even your region is set to somewhere in Europe.
I realized though that if you put for example "france ru" it gives you france locations only matching ru which is perfect.
So my problem is that the autocomple is completely built by google javascript.
autocomplete = new google.maps.places.Autocomplete(input, options);
So I cannot easily fiddle with search string to add in to it constantly "france"
I can see what is bound to the onkeyup event on that field and can take it and call it myself however I cannot unbind it from keyup. I tried several solutions how to do it but can't find a way. jQuery unbind won't work as this is not bound through it obviously. Native functions want a reference to a function bind to listener but this is annonymous function in it. Found some examples using loops over element.data['events'] but I get data undefined error.
Has anyone solution to unbind all what is register in onkeyup ?

You mentioned jQuery, so I'll use that:
$(input).data('events').keyup is the array that will contain all the keyup handlers. If there is only one keyup event used by Autocomplete, you can hijack the handler to first run whatever function you need, then run the original:
var originalKeyup = $(input).data('events').keyup[0].handler;
$(input).data('events').keyup[0].handler = function(){
// your code here, where you can add 'france' to input.value
// fire the old function
originalKeyup.apply(this,arguments);
};
You could also just remove the original event handler from the keyup array, and bind new ones that will do what you want.
UPDATE:
You could hijack Element.prototype.addEventListener (BEFORE ALL OTHER CODE) to add an events property to the Element which will contain any handlers added by any code:
var oldAddEventListener = Element.prototype.addEventListener || Element.prototype.attachEvent;
Element.prototype.addEventListener = Element.prototype.attachEvent = function(type, handler){
this.events = this.events || {};
this.events[type] = this.events[type] || [];
this.events[type].push({handler: handler})
oldAddEventListener.apply(this,arguments);
};
Now, every time addEventListener is called, by jQuery or otherwise, the Element's events property should be updated with the current events. You may also want to hijack removeEventListener to remove the corresponding event from the events object when removeEventListener is called:
var oldREL = Element.prototype.removeEventListener || Element.prototype.detachEvent;
Element.prototype.removeEventListener = Element.prototype.detachEvent = function(type, handler){
this.oldREL.apply(this,arguments);
if(this.events && this.events[type]){
for(var i=this.events[type].length-1; i>=0; i--){
if(this.events[type][i].handler == handler){
this.events[type].splice(i,1);
break; // remove only the first occurrence from the end
}
}
if(this.events[type].length==0){
delete this.events[type];
}
}
};
Now you should be able to inspect all events registered on any element. You can remove all 'keyup' events by iterating over the input.events.keyup object and using input.removeEventListener.
The attachEvent and detachEvent are used by IE<9. I don't have IE, so it hasn't been tested there. It works well in Safari 5. Let me know if you have issues in other browsers.
NOTE: These mods need to be in place BEFORE any other code is executed on the page.
Update:
Apparently, this will not work in FF or Opera. Changing Element to HTMLInputElement in the code will fix the problem.

Have you tried binding the autocomplete to the current map bounds, as shown in the documentation: autocomplete.bindTo('bounds', map) ?

jQuery Tips and Tricks

Locked. This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions.
Syntax
Shorthand for the ready-event by roosteronacid
Line breaks and chainability by roosteronacid
Nesting filters by Nathan Long
Cache a collection and execute commands on the same line by roosteronacid
Contains selector by roosteronacid
Defining properties at element creation by roosteronacid
Access jQuery functions as you would an array by roosteronacid
The noConflict function - Freeing up the $ variable by Oli
Isolate the $ variable in noConflict mode by nickf
No-conflict mode by roosteronacid
Data Storage
The data function - bind data to elements by TenebrousX
HTML5 data attributes support, on steroids! by roosteronacid
The jQuery metadata plug-in by Filip Dupanović
Optimization
Optimize performance of complex selectors by roosteronacid
The context parameter by lupefiasco
Save and reuse searches by Nathan Long
Creating an HTML Element and keeping a reference, Checking if an element exists, Writing your own selectors by Andreas Grech
Miscellaneous
Check the index of an element in a collection by redsquare
Live event handlers by TM
Replace anonymous functions with named functions by ken
Microsoft AJAX framework and jQuery bridge by Slace
jQuery tutorials by egyamado
Remove elements from a collection and preserve chainability by roosteronacid
Declare $this at the beginning of anonymous functions by Ben
FireBug lite, Hotbox plug-in, tell when an image has been loaded and Google CDN by Colour Blend
Judicious use of third-party jQuery scripts by harriyott
The each function by Jan Zich
Form Extensions plug-in by Chris S
Asynchronous each function by OneNerd
The jQuery template plug-in: implementing complex logic using render-functions by roosteronacid

Creating an HTML Element and keeping a reference
var newDiv = $("<div />");
newDiv.attr("id", "myNewDiv").appendTo("body");
/* Now whenever I want to append the new div I created,
I can just reference it from the "newDiv" variable */
Checking if an element exists
if ($("#someDiv").length)
{
// It exists...
}
Writing your own selectors
$.extend($.expr[":"], {
over100pixels: function (e)
{
return $(e).height() > 100;
}
});
$(".box:over100pixels").click(function ()
{
alert("The element you clicked is over 100 pixels height");
});

jQuery's data() method is useful and not well known. It allows you to bind data to DOM elements without modifying the DOM.

Nesting Filters
You can nest filters (as nickf showed here).
.filter(":not(:has(.selected))")

I'm really not a fan of the $(document).ready(fn) shortcut. Sure it cuts down on the code but it also cuts way down on the readability of the code. When you see $(document).ready(...), you know what you're looking at. $(...) is used in far too many other ways to immediately make sense.
If you have multiple frameworks you can use jQuery.noConflict(); as you say, but you can also assign a different variable for it like this:
var $j = jQuery.noConflict();
$j("#myDiv").hide();
Very useful if you have several frameworks that can be boiled down to $x(...)-style calls.

Ooooh, let's not forget jQuery metadata! The data() function is great, but it has to be populated via jQuery calls.
Instead of breaking W3C compliance with custom element attributes such as:
<input
name="email"
validation="required"
validate="email"
minLength="7"
maxLength="30"/>
Use metadata instead:
<input
name="email"
class="validation {validate: email, minLength: 2, maxLength: 50}" />
<script>
jQuery('*[class=validation]').each(function () {
var metadata = $(this).metadata();
// etc.
});
</script>

Live Event Handlers
Set an event handler for any element that matches a selector, even if it gets added to the DOM after the initial page load:
$('button.someClass').live('click', someFunction);
This allows you to load content via ajax, or add them via javascript and have the event handlers get set up properly for those elements automatically.
Likewise, to stop the live event handling:
$('button.someClass').die('click', someFunction);
These live event handlers have a few limitations compared to regular events, but they work great for the majority of cases.
For more info see the jQuery Documentation.
UPDATE: live() and die() are deprecated in jQuery 1.7. See http://api.jquery.com/on/ and http://api.jquery.com/off/ for similar replacement functionality.
UPDATE2: live() has been long deprecated, even before jQuery 1.7. For versions jQuery 1.4.2+ before 1.7 use delegate() and undelegate(). The live() example ($('button.someClass').live('click', someFunction);) can be rewritten using delegate() like that: $(document).delegate('button.someClass', 'click', someFunction);.

Replace anonymous functions with named functions. This really supercedes the jQuery context, but it comes into play more it seems like when using jQuery, due to its reliance on callback functions. The problems I have with inline anonymous functions, are that they are harder to debug (much easier to look at a callstack with distinctly-named functions, instead 6 levels of "anonymous"), and also the fact that multiple anonymous functions within the same jQuery-chain can become unwieldy to read and/or maintain. Additionally, anonymous functions are typically not re-used; on the other hand, declaring named functions encourages me to write code that is more likely to be re-used.
An illustration; instead of:
$('div').toggle(
function(){
// do something
},
function(){
// do something else
}
);
I prefer:
function onState(){
// do something
}
function offState(){
// do something else
}
$('div').toggle( offState, onState );

Defining properties at element creation
In jQuery 1.4 you can use an object literal to define properties when you create an element:
var e = $("<a />", { href: "#", class: "a-class another-class", title: "..." });
... You can even add styles:
$("<a />", {
...
css: {
color: "#FF0000",
display: "block"
}
});
Here's a link to the documentation.

instead of using a different alias for the jQuery object (when using noConflict), I always write my jQuery code by wrapping it all in a closure. This can be done in the document.ready function:
var $ = someOtherFunction(); // from a different library
jQuery(function($) {
if ($ instanceOf jQuery) {
alert("$ is the jQuery object!");
}
});
alternatively you can do it like this:
(function($) {
$('...').etc() // whatever jQuery code you want
})(jQuery);
I find this to be the most portable. I've been working on a site which uses both Prototype AND jQuery simultaneously and these techniques have avoided all conflicts.

Check the Index
jQuery has .index but it is a pain to use, as you need the list of elements, and pass in the element you want the index of:
var index = e.g $('#ul>li').index( liDomObject );
The following is much easier:
If you want to know the index of an element within a set (e.g. list items) within a unordered list:
$("ul > li").click(function () {
var index = $(this).prevAll().length;
});

Shorthand for the ready-event
The explicit and verbose way:
$(document).ready(function ()
{
// ...
});
The shorthand:
$(function ()
{
// ...
});

On the core jQuery function, specify the context parameter in addition to the selector parameter. Specifying the context parameter allows jQuery to start from a deeper branch in the DOM, rather than from the DOM root. Given a large enough DOM, specifying the context parameter should translate to performance gains.
Example: Finds all inputs of type radio within the first form in the document.
$("input:radio", document.forms[0]);
Reference: http://docs.jquery.com/Core/jQuery#expressioncontext

Not really jQuery only but I made a nice little bridge for jQuery and MS AJAX:
Sys.UI.Control.prototype.j = function Sys$UI$Control$j(){
return $('#' + this.get_id());
}
It's really nice if you're doing lots of ASP.NET AJAX, since jQuery is supported by MS now having a nice bridge means it's really easy to do jQuery operations:
$get('#myControl').j().hide();
So the above example isn't great, but if you're writing ASP.NET AJAX server controls, makes it easy to have jQuery inside your client-side control implementation.

Optimize performance of complex selectors
Query a subset of the DOM when using complex selectors drastically improves performance:
var subset = $("");
$("input[value^='']", subset);

Speaking of Tips and Tricks and as well some tutorials. I found these series of tutorials (“jQuery for Absolute Beginners” Video Series) by Jeffery Way are VERY HELPFUL.
It targets those developers who are new to jQuery. He shows how to create many cool stuff with jQuery, like animation, Creating and Removing Elements and more...
I learned a lot from it. He shows how it's easy to use jQuery.
Now I love it and i can read and understand any jQuery script even if it's complex.
Here is one example I like "Resizing Text"
1- jQuery...
<script language="javascript" type="text/javascript">
$(function() {
$('a').click(function() {
var originalSize = $('p').css('font-size'); // get the font size
var number = parseFloat(originalSize, 10); // that method will chop off any integer from the specified variable "originalSize"
var unitOfMeasure = originalSize.slice(-2);// store the unit of measure, Pixle or Inch
$('p').css('font-size', number / 1.2 + unitOfMeasure);
if(this.id == 'larger'){$('p').css('font-size', number * 1.2 + unitOfMeasure);}// figure out which element is triggered
});
});
</script>
2- CSS Styling...
<style type="text/css" >
body{ margin-left:300px;text-align:center; width:700px; background-color:#666666;}
.box {width:500px; text-align:justify; padding:5px; font-family:verdana; font-size:11px; color:#0033FF; background-color:#FFFFCC;}
</style>
2- HTML...
<div class="box">
Larger |
Smaller
<p>
In today’s video tutorial, I’ll show you how to resize text every time an associated anchor tag is clicked. We’ll be examining the “slice”, “parseFloat”, and “CSS” Javascript/jQuery methods.
</p>
</div>
Highly recommend these tutorials...
http://blog.themeforest.net/screencasts/jquery-for-absolute-beginners-video-series/

Asynchronous each() function
If you have really complex documents where running the jquery each() function locks up the browser during the iteration, and/or Internet Explorer pops up the 'do you want to continue running this script' message, this solution will save the day.
jQuery.forEach = function (in_array, in_pause_ms, in_callback)
{
if (!in_array.length) return; // make sure array was sent
var i = 0; // starting index
bgEach(); // call the function
function bgEach()
{
if (in_callback.call(in_array[i], i, in_array[i]) !== false)
{
i++; // move to next item
if (i < in_array.length) setTimeout(bgEach, in_pause_ms);
}
}
return in_array; // returns array
};
jQuery.fn.forEach = function (in_callback, in_optional_pause_ms)
{
if (!in_optional_pause_ms) in_optional_pause_ms = 10; // default
return jQuery.forEach(this, in_optional_pause_ms, in_callback); // run it
};
The first way you can use it is just like each():
$('your_selector').forEach( function() {} );
An optional 2nd parameter lets you specify the speed/delay in between iterations which may be useful for animations (the following example will wait 1 second in between iterations):
$('your_selector').forEach( function() {}, 1000 );
Remember that since this works asynchronously, you can't rely on the iterations to be complete before the next line of code, for example:
$('your_selector').forEach( function() {}, 500 );
// next lines of code will run before above code is complete
I wrote this for an internal project, and while I am sure it can be improved, it worked for what we needed, so hope some of you find it useful. Thanks -

Syntactic shorthand-sugar-thing--Cache an object collection and execute commands on one line:
Instead of:
var jQueryCollection = $("");
jQueryCollection.command().command();
I do:
var jQueryCollection = $("").command().command();
A somewhat "real" use case could be something along these lines:
var cache = $("#container div.usehovereffect").mouseover(function ()
{
cache.removeClass("hover").filter(this).addClass("hover");
});

I like declare a $this variable at the beginning of anonymous functions, so I know I can reference a jQueried this.
Like so:
$('a').each(function() {
var $this = $(this);
// Other code
});

Save jQuery Objects in Variables for Reuse
Saving a jQuery object to a variable lets you reuse it without having to search back through the DOM to find it.
(As #Louis suggested, I now use $ to indicate that a variable holds a jQuery object.)
// Bad: searching the DOM multiple times for the same elements
$('div.foo').each...
$('div.foo').each...
// Better: saving that search for re-use
var $foos = $('div.foo');
$foos.each...
$foos.each...
As a more complex example, say you've got a list of foods in a store, and you want to show only the ones that match a user's criteria. You have a form with checkboxes, each one containing a criteria. The checkboxes have names like organic and lowfat, and the products have corresponding classes - .organic, etc.
var $allFoods, $matchingFoods;
$allFoods = $('div.food');
Now you can keep working with that jQuery object. Every time a checkbox is clicked (to check or uncheck), start from the master list of foods and filter down based on the checked boxes:
// Whenever a checkbox in the form is clicked (to check or uncheck)...
$someForm.find('input:checkbox').click(function(){
// Start out assuming all foods should be showing
// (in case a checkbox was just unchecked)
var $matchingFoods = $allFoods;
// Go through all the checked boxes and keep only the foods with
// a matching class
this.closest('form').find("input:checked").each(function() {
$matchingFoods = $matchingFoods.filter("." + $(this).attr("name"));
});
// Hide any foods that don't match the criteria
$allFoods.not($matchingFoods).hide();
});

It seems that most of the interesting and important tips have been already mentioned, so this one is just a little addition.
The little tip is the jQuery.each(object, callback) function. Everybody is probably using the jQuery.each(callback) function to iterate over the jQuery object itself because it is natural. The jQuery.each(object, callback) utility function iterates over objects and arrays. For a long time, I somehow did not see what it could be for apart from a different syntax (I don’t mind writing all fashioned loops), and I’m a bit ashamed that I realized its main strength only recently.
The thing is that since the body of the loop in jQuery.each(object, callback) is a function, you get a new scope every time in the loop which is especially convenient when you create closures in the loop.
In other words, a typical common mistake is to do something like:
var functions = [];
var someArray = [1, 2, 3];
for (var i = 0; i < someArray.length; i++) {
functions.push(function() { alert(someArray[i]) });
}
Now, when you invoke the functions in the functions array, you will get three times alert with the content undefined which is most likely not what you wanted. The problem is that there is just one variable i, and all three closures refer to it. When the loop finishes, the final value of i is 3, and someArrary[3] is undefined. You could work around it by calling another function which would create the closure for you. Or you use the jQuery utility which it will basically do it for you:
var functions = [];
var someArray = [1, 2, 3];
$.each(someArray, function(item) {
functions.push(function() { alert(item) });
});
Now, when you invoke the functions you get three alerts with the content 1, 2 and 3 as expected.
In general, it is nothing you could not do yourself, but it’s nice to have.

Access jQuery functions as you would an array
Add/remove a class based on a boolean...
function changeState(b)
{
$("selector")[b ? "addClass" : "removeClass"]("name of the class");
}
Is the shorter version of...
function changeState(b)
{
if (b)
{
$("selector").addClass("name of the class");
}
else
{
$("selector").removeClass("name of the class");
}
}
Not that many use-cases for this. Never the less; I think it's neat :)
Update
Just in case you are not the comment-reading-type, ThiefMaster points out that the toggleClass accepts a boolean value, which determines if a class should be added or removed. So as far as my example code above goes, this would be the best approach...
$('selector').toggleClass('name_of_the_class', true/false);

Update:
Just include this script on the site and you’ll get a Firebug console that pops up for debugging in any browser. Not quite as full featured but it’s still pretty helpful! Remember to remove it when you are done.
<script type='text/javascript' src='http://getfirebug.com/releases/lite/1.2/firebug-lite-compressed.js'></script>
Check out this link:
From CSS Tricks
Update:
I found something new; its the the JQuery Hotbox.
JQuery Hotbox
Google hosts several JavaScript libraries on Google Code. Loading it from there saves bandwidth and it loads quick cos it has already been cached.
<script src="http://www.google.com/jsapi"></script>
<script type="text/javascript">
// Load jQuery
google.load("jquery", "1.2.6");
google.setOnLoadCallback(function() {
// Your code goes here.
});
</script>
Or
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js" type="text/javascript"></script>
You can also use this to tell when an image is fully loaded.
$('#myImage').attr('src', 'image.jpg').load(function() {
alert('Image Loaded');
});
The "console.info" of firebug, which you can use to dump messages and variables to the screen without having to use alert boxes. "console.time" allows you to easily set up a timer to wrap a bunch of code and see how long it takes.
console.time('create list');
for (i = 0; i < 1000; i++) {
var myList = $('.myList');
myList.append('This is list item ' + i);
}
console.timeEnd('create list');

Use filtering methods over pseudo selectors when possible so jQuery can use querySelectorAll (which is much faster than sizzle). Consider this selector:
$('.class:first')
The same selection can be made using:
$('.class').eq(0)
Which is must faster because the initial selection of '.class' is QSA compatible

Remove elements from a collection and preserve chainability
Consider the following:
<ul>
<li>One</li>
<li>Two</li>
<li>Three</li>
<li>Four</li>
<li>Five</li>
</ul>
$("li").filter(function()
{
var text = $(this).text();
// return true: keep current element in the collection
if (text === "One" || text === "Two") return true;
// return false: remove current element from the collection
return false;
}).each(function ()
{
// this will alert: "One" and "Two"
alert($(this).text());
});
The filter() function removes elements from the jQuery object. In this case: All li-elements not containing the text "One" or "Two" will be removed.

Changing the type of an input element
I ran into this issue when I was trying to change the type of an input element already attached to the DOM. You have to clone the existing element, insert it before the old element, and then delete the old element. Otherwise it doesn't work:
var oldButton = jQuery("#Submit");
var newButton = oldButton.clone();
newButton.attr("type", "button");
newButton.attr("id", "newSubmit");
newButton.insertBefore(oldButton);
oldButton.remove();
newButton.attr("id", "Submit");

Judicious use of third-party jQuery scripts, such as form field validation or url parsing. It's worth seeing what's about so you'll know when you next encounter a JavaScript requirement.

Line-breaks and chainability
When chaining multiple calls on collections...
$("a").hide().addClass().fadeIn().hide();
You can increase readability with linebreaks. Like this:
$("a")
.hide()
.addClass()
.fadeIn()
.hide();

Use .stop(true,true) when triggering an animation prevents it from repeating the animation. This is especially helpful for rollover animations.
$("#someElement").hover(function(){
$("div.desc", this).stop(true,true).fadeIn();
},function(){
$("div.desc", this).fadeOut();
});

Using self-executing anonymous functions in a method call such as .append() to iterate through something. I.E.:
$("<ul>").append((function ()
{
var data = ["0", "1", "2", "3", "4", "5", "6"],
output = $("<div>"),
x = -1,
y = data.length;
while (++x < y) output.append("<li>" + info[x] + "</li>");
return output.children();
}()));
I use this to iterate through things that would be large and uncomfortable to break out of my chaining to build.

HTML5 data attributes support, on steroids!
The data function has been mentioned before. With it, you are able to associate data with DOM elements.
Recently the jQuery team has added support for HTML5 custom data-* attributes. And as if that wasn't enough; they've force-fed the data function with steroids, which means that you are able to store complex objects in the form of JSON, directly in your markup.
The HTML:
<p data-xyz = '{"str": "hi there", "int": 2, "obj": { "arr": [1, 2, 3] } }' />
The JavaScript:
var data = $("p").data("xyz");
data.str // "hi there"
typeof data.str // "string"
data.int + 2 // 4
typeof data.int // "number"
data.obj.arr.join(" + ") + " = 6" // "1 + 2 + 3 = 6"
typeof data.obj.arr // "object" ... Gobbles! Errrghh!