Getting started with jQuery
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The document provides an overview of jQuery, a popular JavaScript library aimed at simplifying client-side scripting. It covers key fundamentals such as DOM manipulation, event handling, animations, AJAX requests, and jQuery UI features, emphasizing its lightweight nature, ease of use, and extensive community support. It also discusses the benefits of using jQuery in conjunction with various frameworks and offers guidance on writing plugins and utilizing CDNs.
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Getting started with jQuery
- 1. Getting started with jQuery Gill Cleeren @gillcleeren
- 2. Hi, I‟m Gill! Gill Cleeren MVP and Regional Director .NET Architect @ Ordina Trainer & speaker @gillcleeren [email protected]
- 3. What we‟ll be looking at... • Why jQuery? • jQuery fundamentals • Creating and manipulating elements • Events • Animations and effects • Talking to the server • jQuery UI • Writing plugins • Breaking news around new releases • Using the CDN
- 4. Throughout the session... •You‟ll see some •Goal: show a particular place where jQuery really stands out
- 5. Hi, jQuery • jQuery is • Most popular, cross-browser JavaScript library • Focusing on making client-side scripting of HTML simpler • Easy navigating the DOM • Handling events • Working with Ajax • Open-source, first released in 2006 • Current release is 1.9 and 2.1 • Same API • 2.X branch doesn‟t support IE 6, 7 and 8 – Recommended to use 1.X for public sites
- 6. Why jQuery? • Many JavaScript frameworks try bending the language out of its natural form • jQuery aims at leveraging CSS, HTML and JavaScript • Advantages • Lightweight • Easy to learn using familiar CSS syntax and intuitive • Many plugins available • Easy to extend and compatible • It‟s on Microsoft‟s radar • Rich community $('#something').hide().css('background', 'red').fadeIn();
- 7. You are not alone! • Many LARGE companies use jQuery for their sites, including:
- 8. Microsoft and jQuery •Included with Visual Studio in both WebForms and MVC projects for a couple of versions already • Can be used with or without ScriptManager • IntelliSense available • CDN support (more later) •Microsoft is contributor to jQuery • Created templating, data linking and globalization (2010) • Not actively maintained now though
- 9. Script, don‟t get in my way! • jQuery helps us writing Unobstrutive JavaScript code • You don‟t want to mingle style with HTML • Why would you want to mingle behavior with HTML? • This will become a heavy job without jQuery!
- 10. jQuery fundamentals: $ •$ function (aka jQuery() function) returns • A JavaScript object containing an array of DOM elements • In the order they were found in the document • Matching a specified selector (for example a CSS selector) • Known to mankind as a wrapper or wrapped set •It returns the same group of elements, can be chained
- 11. jQuery fundamentals: the ready handler • Script execution should wait until DOM elements are ready • You say: window.onload? • Sadly, this waits for everything to be loaded, including images etc • Script execution is too late • Instead, we need to wait only until the DOM tree is created • Can be difficult in cross-browser situations • Easy-peasy with jQuery
- 12. jQuery fundamentals: selectors •At the core of jQuery lies its selector engine • Can be used to select elements based on names, attribute, position... •$() is heavily overloaded • Making a selection • Creating new HTML elements
- 13. jQuery fundamentals: selectors •Most basic: CSS selectors • Can be combined •Child selector •Attribute selector
- 14. jQuery fundamentals: selectors •Position •Psuedo-classes (CSS filter selectors & custom selectors)
- 15. More selectors Full list at http://www.w3.org/TR/css3- selectors/Pattern Meaning * any element E an element of type E E[foo] an E element with a "foo" attribute E[foo^="bar"] an E element whose "foo" attribute value begins exactly with the string "bar" E:nth-child(n) an E element, the n-th child of its parent E:first-child an E element, first child of its parent E:empty an E element that has no children (including text nodes) E:link E:visited an E element being the source anchor of a hyperlink of which the target is not yet visited (:link) or already visited (:visited) E > F an F element child of an E element E + F an F element immediately preceded by an E element
- 16. DEMO Selecting elements using selectors
- 17. jQuery fundamentals: creating elements •$(„...‟) selects an element <> $(„<li>‟) creates an element • Attributes can be passed using JavaScript object
- 19. Working with the result of $ •Once we have a wrapped set, we can go wild with it! • Handle the set as a whole • Work with individual elements
- 20. Working with the result of $ •A wrapped set is like an array of elements, normal “array operations” can be done on it • Check the size • Access an indiviual element • Loop over the elements
- 21. Working with the result of $ •Set operations (continued) • Add and remove elements • Filter elements •Remember that we are always returning the set • Chaining is always possible!
- 22. DEMO Working with the set
- 23. Attributes • When we want to change how an element looks, we can change its attributes • jQuery provides the attr() method • 2 variations based on number and types of parameters • Read a specified property from first element in wrapped set • Set a property on all elements in the wrapped set (0 or more) – Can also accept a function • Attr() helps us dealing with browser-dependencies (again) • jQuery float attribute refers to styleFloat in IE, cssFloat in others
- 24. Attributes (2) •jQuery makes it easy to apply and remove CSS classes • addClass(), removeClass(), toggleClass() and hasClass() •Changing indiviual CSS elements is supported • css() can be used to get or set CSS on an element$('#mydiv').css("background-color","yellow");
- 25. Working with elements •html() can be used to get or set the content of an element • text() can retrieve combined textual content of all elements, including their children •If the elements are form elements, we need to use val() $('input:checkbox:checked').val(); $('#mydiv').html();
- 27. Events • A bit of history • Once upon a time, a browser called Netscape introduced an event model, often referred to as DOM Level 0 Event Model • Creates event handlers as references to a function on a property • Not what we need if we want to create Unobtrusive JavaScript • Only one event handler per element for specific event • Only got standardized until DOM Level 2 Event Model • Based on a system of event listeners (addEventListener) • IE decided to go its own way (attachEvent) • Using event was a real mess because of browser dependencies • jQuery comes to the rescue
- 28. jQuery events •on() is where it all starts • Binds a function to any event on any DOM element • off() can be used to unbind a function from an event • Replaces the bind() and unbind() • Works in any browser, jQuery hides the details for us • Possible to bind more than one event handler for an event on on element •one() removes itself after event handler executed
- 29. DEMO Events
- 30. Animations and effects • Core jQuery has some basic effects • More are available in jQuery UI • Should be used with caution! • Most basic „animation‟ is hiding/showing an element • hide(): sets display:none on the element • show(): sets display to inline/block • toggle(): sets visible is hidden and vice-versa • Methods are overloaded, accepting • Speed • Callback
- 31. Animations and effects (2) •Elements can also be gradually added/removed • slideDown() and slideUp() •Fading in is supported as well • fadeIn() and fadeOut() •animate() is mother of all animations • Using „target values‟ for style properties, jQuery will animate the transition
- 32. DEMO Animations
- 33. Ajax in the past • When we were all young (in 1998), Microsoft introduced the ability to perform asynchronous requests from script (ActiveX) • Later, other browsers implemented a standard, the XMLHttpRequest • IE6 uses an ActiveX object • Result is that we need to do checks • Again... jQuery to the rescue! if(window.ActiveXObject) { xhr = new ActiveXObject("Microsoft.XMLHTTP"); } else if (window.XMLHttpRequest) { xhr = new XMLHttpRequest(); }
- 34. Ajax with jQuery • Basic functionality to load content from a server-side resource: • load() • url • parameters: data to be passed (string, object...). If provided, a POST is executed, otherwise a GET • callback (optional) • Next to load, we can also use $.get()/$.getJson() or $.post() $('#someDiv') .load('test.html', function() { alert('Load was performed.'); });
- 35. DEMO Basic Ajax request with load()
- 36. Ajax with jQuery •If we need all control over the Ajax request we can get: • $.ajax() • options: defines an object containing all the properties for the Ajax request •List of options is huge, therefore • $.ajaxSetup • options: defines an object containing all the properties for the Ajax request, becoming the default for Ajax requests
- 37. Ajax with jQuery •Throughout the Ajax request, we can get feedback • Local events from the $.ajax() call (callbacks) • Global events • Are broadcast to every element within the DOM, can be attached on any element – ajaxStart – ajaxSend – ajaxSuccess – ajaxError – ajaxComplete
- 38. DEMO More control with ajax()
- 39. jQuery Ajax, ASP.NET MVC and WebForms •jQuery can work in harmony with ASP.NET MVC and WebForms • Sample ajax() call for WebForms $.ajax({ type: "post", contentType: "application/json; charset=utf-8", dataType: "json", url: "/Default.aspx/AddTask", data: JSON.stringify(dto) });
- 40. DEMO ASP.NET WebForms with jQuery
- 41. DEMO ASP.NET MVC with jQuery
- 42. jQuery UI • Huge extension of jQuery, providing more UI capabilities • Contains number of UI features we‟d logically need • Includes • Effects: more advanced than core effects • Interactions: drag and drop • Widgets (aka controls): date picker... • All can be themed • jqueryui.com contains tool to configure download and “ThemeRoller” tool • Code included in jquery-ui.js
- 43. jQueryUI Themes •Themes come with the download • It‟s *never* going to be OK for the marketing guys! • Options • Use it anyway • Use the ThemeRoller • Tweak a default or custom-created one • Create one yourself (Warning: the CSS is quite large)
- 44. Effects • jQuery core contains some basic effects • Based on the effect(type, options, speed, callback) method • Has several animation types such as puff, highlight and shake (even explode exists) • Also allows to do animations with colors (not possible with animate()) • backgroundColor, color... • Visibility methods (show()...) are extended • Class methods (addClass()...) are extended • position() method is added for advanced positioning $('#someElement').position({ my: 'top center', at: 'bottom right', of: '#someOtherElement'});
- 45. DEMO Effects
- 46. Interactions • Interactions focus on allowing users to directly interact with elements, which isn‟t possible with standard HTML controls • They add advanced behaviors to our pages related to mouse interactions • Available interactions: • Dragging • Dropping • Sorting • Resizing • Selecting
- 47. Dragging •Easy-peasy (again) with jQuery •draggable() is your friend (heavily overloaded once again) • Allows making elements draggable, possible with options (opacity...) • Overloaded so it also support enabling, disabling... Draggable
- 48. DEMO Dragging, dropping and other interactions
- 49. Widgets: controls on steroids • New controls (based on existing ones) • Contents • Buttons • Sliders • Progress bars • Autocompletion • Date picker • Tabs • Accordion • Dialog box
- 50. Date picker •Have you noticed that entering dates is a difficult thing for end users? Some will always get it wrong! •jQuery UI‟s DatePicker can help • $.datepicker() creates the control for you • Has numerous options, mostly default will do • $.datepicker.setDefaults() can be used to share defaults
- 51. Dialog Box • In fact, a dialog box is nothing more that a DIV with a higher z-index and some custom chrome • jQuery will handle the nasty details for us (once again) • About every element can become the content of the dialog box • On a wrapped set, use .dialog() to make it appear as such • Triggers some events, such as close, drag and resize • Adds classes on the elements • ui-dialog • ui-dialog-title • ...
- 53. Something missing in jQuery? •2 options: • Use an existing plugin • jQuery plugin repository: plugins.jquery.com • Google code: code.google.com • SourceForge: sourceforge.net • GitHub: github.com • Write a plugin yourself • Custom utility function • Create wrapper functions
- 55. Writing your own plugins •Write a plugin to add it yourself! • Possible to write your own utility functions and wrapper methods •Creating new wrapper methods: • Add the method as a property on the fn object in the $ namespace
- 57. Where to get your stuff? •Use a CDN? • Microsoft • Google •Put scripts locally as well with a fallback mechanism<script type="text/javascript" src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.min.js"> </script> <script type="text/javascript"> if (typeof jQuery == 'undefined') { document.write(unescape("%3Cscript src='/Scripts/jquery-1.4.2.min.js' type='text/javascript'%3E%3C/script%3E")); } </script>
- 58. Summary •Where does all the (l) for jQuery come from? • Light-weight library that uses JavaScript as JavaScript, relying on CSS • Cross-browser compatible, hides the details (ready handler) • Easy eventing model • Can work with MVC & WebForms • Easily extensible to fit your needs, tons of plugins already available
- 59. So I hope you now say too...
- 60. Questions?
- 61. Thank you!
- 62. Getting started with jQuery Gill Cleeren @gillcleeren