jQuery
File:Jquerylogo.png | |
Developer(s) | jQuery Team |
---|---|
Stable release | 1.3.2
/ February 20, 2009 |
Repository | |
Written in | JavaScript |
Type | Web application framework |
License | Dual license: GPL and MIT |
Website | http://jquery.com/ |
jQuery is a lightweight JavaScript library that emphasizes interaction between JavaScript and HTML. It was released in January 2006 at BarCamp NYC by John Resig.
Dual-licensed under the MIT License and the GNU General Public License, jQuery is free, open source software.
Both Microsoft and Nokia have announced plans to bundle jQuery on their platforms,[1] Microsoft adopting it initially within Visual Studio[2] for use within Microsoft's ASP.NET AJAX framework and ASP.NET MVC Framework whilst Nokia will integrate it into their Web Run-Time platform.
Philosophy
Just as CSS separates "display" characteristics from the HTML structure, jQuery separates the "behavior" characteristics from the HTML structure. For example, instead of directly specifying the on-click event handler in the specification of a button element, a jQuery driven page would first identify the button element, and then modify its onclick event handler. This separation of behavior from structure is also referred to as the principle of Unobtrusive JavaScript.
Features
jQuery contains the following features:
- DOM element selections using the cross-browser open source selector engine Sizzle, a spin-off out of jQuery project[3]
- DOM traversal and modification (including support for CSS 1-3 and basic XPath)
- Events
- CSS manipulation
- Effects and animations
- Ajax
- Extensibility
- Utilities - such as browser version and the
each
function. - JavaScript Plugins
The $ function
One of the critical concepts in any jQuery code is the so called '$' function. '$' is actually an 'alias' for the 'jQuery' namespace.
Example 1: jQuery provides a function for trimming strings. This function can be used as:
str = " foo ";
jQuery.trim(str); // returns "foo"
Or, it can also be used as:
str = " foo ";
$.trim(str);
These are equivalent. Usage of '$' instead of 'jQuery' is an ad-hoc convention and is considered to be a faster way of accessing the JQuery library.
Example 2: To select all the paragraphs that have the class 'foo' and add another class called 'bar' to all of them:
$("p.foo").addClass("bar");
Example 3: To execute a function 'myfunc' immediately after the page is loaded (called the ready handler in jQuery lingo):
$(document).ready(function() {
myfunc();
});
This is typically used in a context like this:
$(document).ready(function() {
// Stripe all the tables in the document using the oddStripe and evenStripe CSS classes.
$('tr:nth-child(odd)').addClass("oddStripe");
$('tr:nth-child(even)').addClass("evenStripe");
});
Use
jQuery usually exists as a single JavaScript file, containing all the common DOM, Event, Effects, and Ajax functions. It can be included within any web page by using the following mark-up:
<script type="text/javascript" src="/path/to/jQuery.js"></script>
The latest stable versions of jQuery can also be loaded using the Google AJAX Libraries API. This method of obtaining the library has many benefits including unified caching and decreased latency and can be included with the following mark-up:
<script type="text/javascript" src="http://www.google.com/jsapi"></script>
<script>
google.load("jquery", "1.3.2");
</script>
Another popular way is to load the jQuery library directly from Google's servers:
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
[4] jQuery has two styles of interaction:
- via the
$
function, which is a factory method for the jQuery object. These functions, often called commands, are chainable; they each return the jQuery object - via
$.
-prefixed functions. These are utility functions which do not work on the jQuery object per se.
A typical workflow for manipulation of multiple DOM nodes begins with $
function being called with a CSS selector string, which results in the jQuery object referencing zero or more elements in the HTML page. This node set can be manipulated by applying instance methods to the jQuery object, or the nodes themselves can be manipulated. For example:
$("div.test").add("p.quote").addClass("blue").slideDown("slow");
…finds the union of all div
tags with class attribute test
and all p
tags with class attribute quote
, adds the class attribute blue
to each matched element, and then slides them down with an animation. The $
and add
functions affect the matched set, while the addClass
and slideDown
affect the referenced nodes.
The methods prefixed with $.
are convenience methods or affect global properties and behaviour. For example, the following is an example of the map function called each
in jQuery:
$.each([1,2,3], function() {
document.write(this + 1);
});
... writes 234
to the document.
It is possible to perform Ajax routines using the $.ajax
and associated methods to load and manipulate remote data.
$.ajax({
type: "POST",
url: "some.php",
data: "name=John&location=Boston",
success: function(msg){
alert( "Data Saved: " + msg );
}
});
... will request some.php
with parameters name=John
and location=Boston
and when the request is finished successfully, the response will be alerted.
Release history
Release date | Version number | Additional notes |
---|---|---|
February 20, 2009 | 1.3.2 | |
January 21, 2009 | 1.3.1 | |
January 14, 2009 | 1.3 | Sizzle Selector Engine introduced into core |
May 24, 2008 | 1.2.6 | |
May 21, 2008 | 1.2.5 | Fix for bad build of 1.2.4 |
May 19, 2008 | 1.2.4 | |
February 8, 2008 | 1.2.3 | |
January 15, 2008 | 1.2.2 | |
September 16, 2007 | 1.2.1 | |
September 10, 2007 | 1.2 | |
August 24, 2007 | 1.1.4 | |
July 5, 2007 | 1.1.3.1 | |
July 1, 2007 | 1.1.3 | |
May 20, 2007 | 1.1.3a | Alpha Release |
February 27, 2007 | 1.1.2 | |
January 22, 2007 | 1.1.1 | |
January 14, 2007 | 1.1 | |
January 8, 2007 | 1.1a | Alpha Release |
December 12, 2006 | 1.0.4 | Last 1.0 bug fix |
October 27, 2006 | 1.0.3 | |
October 9, 2006 | 1.0.2 | |
August 31, 2006 | 1.0.1 | |
August 26, 2006 | 1.0 | First Stable Release |
June 30, 2006 | 1.0a | Alpha Release |
See also
References
- ^ Resig, John (2008-09-28). "jQuery, Microsoft, and Nokia". jQuery Blog. jQuery. Retrieved 2009-01-29.
- ^ Guthrie, Scott (2008-09-28). "jQuery and Microsoft". ScottGu's Blog. Retrieved 2009-01-29.
- ^ Resig, John (2009-01-14). "jQuery 1.3 and the jQuery Foundation". jQuery Blog. Retrieved 2009-05-04.
- ^ http://code.google.com/apis/ajaxlibs/documentation/#jquery
- Taft, Darryl K. (2006-08-30). "jQuery Eases JavaScript, AJAX Development". eWeek. Retrieved 2009-05-04.
- Krill, Paul (2006-08-31). "JavaScript, .Net developers aided in separate projects". InfoWorld. Retrieved 2009-05-04.
- John Resig (speaker). Advancing JavaScript with Libraries (Part 1) (Yahoo! Video). YUI Theater. Retrieved 2009-05-04.
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Further reading
- Chaffer, Jonathon (2007). Learning JQuery: Better Interaction Design and Web Development with Simple JavaScript Techniques. Packt Publishing. ISBN 978-1847192509.
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- Darie, Cristian (2005). Ajax And Php: Building Responsive Web Applications. Packt Publishing. ISBN 978-1904811824.
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External links
- Official website
- jQuery Mailing List
- Quick Reference Api
- Simplify Ajax development with jQuery
- Dmitri Gaskin (speaker). jQuery (YouTube). Google Tech Talks. Retrieved 2009-05-04.
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ignored (help) - OOP in jQuery: a small article outlining problems using OOP with jQuery, with several workarounds.
- jQuery for JavaServer Faces: is a library open source of components based on jquery widget.