Jquery In 15 Minutes

jQuery in 15 minutes Torchbox, 7th August 2007

What makes jQuery interesting? • Built around CSS selectors • Well behaved • Doesn’t hijack your global namespace • Plays well with other libraries • API designed with conciseness and convenience as the driving factors

The jQuery() function jQuery('div#intro h2') jQuery('div.section > p') jQuery('input:radio') $('div#intro h2')

jQuery collections • $('div.section') returns a jQuery collection • You can call methods on it: $('div.section').size() = no. of matched elements $('div.section').each(function(div) { // Manipulate the div }

Manipulating collections • Most jQuery methods operate on all of the matched elements in the collection

$('div.section').addClass('highlighted') $('img.photo').attr('src', '/default.png'); $('a.foo').html('<em>Click me now!'); $('p:odd').css('background-color', '#ccc');

Grabbing values • Some methods return results from the first matched element

var height = $('div#intro').height(); var src = $('img.photo').attr('src'); var lastP = $('p:last').html()

Traversing the DOM • jQuery provides enhanced methods for traversing the DOM

$('div.section').next() $('div.section').prev() $('div.section').prev('a') $('div.section').parent() $('div.section').parents()

Handling events • jQuery provides methods for assigning event

handlers to elements in a cross-browser way $('a').click(function(ev) { $(this).css({backgroundColor: 'orange'}); ev.preventDefault(); });

Going unobtrusive $(document).ready(function() { alert('The DOM is ready!'); }); $(function() { alert('This is a shortcut') });

Chaining • Most jQuery methods return another

jQuery object - often one representing the same collection. This means you can chain methods together: $('div.section').hide().addClass('gone');

Crazy chaining $('form#login') // hide all the labels inside the form with the 'optional' class .find('label.optional').hide().end() // add a red border to any password fields in the form .find('input:password').css('border', '1px solid red').end() // add a submit handler to the form .submit(function(){ return confirm('Are you sure you want to submit?'); }); From http://www.ibm.com/developerworks/library/x-ajaxjquery.html

Ajax •

jQuery has excellent support for Ajax $('div#intro').load('/some/file.html');

•

More advanced methods include: $.get(url, params, callback) $.post(url, params, callback) $.getJSON(url, params, callback) $.getScript(url, callback)

Plugins • jQuery is extensible through plugins, which

can add new methods to the jQuery object

• Form: better form manipulation • Dimensions: lots of browser measurements • Interface: fancy effects, accordions • UI: drag and drop, and more

Further reading

• •

http://jquery.com/ - official site http://visualjquery.com/ - useful API reference