jQuery is a JavaScript framework that simplifies client-side scripting. It allows for selecting elements, traversing DOM structures, handling events, and developing animations and AJAX interactions. jQuery abstracts away cross-browser issues and its API is designed to reduce code for common tasks. It has a simple plug-in model for extending functionality and a large community that has built many plug-ins.

1. jQuery Jon Erickson @jonerickson http://jonerickson.me/ http://jonerickson.me/jquery/

2. What is jQuery? JavaScript framework that makes your life easier Selectors & Chaining DOM Traversing DOM Manipulation Event Handling Animations/Effects AJAX Built-in Utilities Extensible Tons of plug-ins built by the community for our use

3. Why jQuery? I’m not an expert at JavaScript The people who created jQuery are! Do not need to worry about cross-browser issues (all abstracted) Light Weight (19 kb compressed) DRY – Simple plug-in model allows for code reuse Animations/Effects are simple Community support is growing rapidly Microsoft adoption (included in MVC template) Tutorials, plug-ins, etc. Client-side scripting is fun with jQuery and breathes some new life into your applications Focus more on the code that solves your problem Amazon, BBC, Dell, Google, IBM, NBC, Netflix, Twitter

4. Sample jQuery Our DOM Include jQuery The ‘ready event’ – Binds a function to be executed whenever the DOM is ready Select the ‘toggleContent’ DOM element and bind a click event handler to it. Select the ‘content’ DOM element and set the text to ‘Hello World!’ Prevent the default behavior of the anchor tag by returning false

5. Dollar Function $(); JavaScript identifiers can start with $ The jQuery framework automatically assigns ‘$’ to the ‘jQuery’ function $ === jQuerytrue $(selector) is same as jQuery(selector) Can use utility function to unassign $ $.noConflict(); $ === jQuery; false Can reassign jQuery to another variable $j = $.noConflict(); $j === jQuery; true $j === $; false $ === jQuery; false

6. Document Ready Event $(document).ready(fn); The bound function will be called the instant the DOM is ready to be read and manipulated. As many as you want on the page. Executed in the order they were added. There is a shortcut: $(fn);

7. Selectors CSS3 Selectors

8. Filters $(‘div:empty’), $(‘:empty’), $(‘div:not(:empty)’) Custom Filter Used

9. Chaining Most jQuery methods return another jQuery object (usually the same collection), which means you can chain method calls together with a fluent like syntax Some methods that stop a chain, these methods return a value from the jQuery object .css(name), .text(), .html(), .val(), .height(), .width(), .is(‘:visible’) Some methods will return a different jQuery collection, you can revert to the previous collection by calling .end();

10. Attributes & Classes Getters & Setters for attr, html, text, val Getter (returns String – breaks chain) var text = $(‘#myDiv’).text(); Setter (returns jQuery) $(‘#myDiv’).text(‘Hello World!’); text() escapes html() val() used with inputs attr() can take JSON Add, Remove for Attributes & Classes .removeAttr(‘someAttr’); .addClass(‘someClass’); .removeClass(‘someClass’); .toggleClass(‘someClass’);

11. Traversing Family parent, parents, siblings, children Proximity closest, next, prev, nextAll, prevAll Searching find

13. Manipulation Inserting Inside append, prepend appendTo, prependTo Inserting Outside after, before insertAfter, insertBefore Inserting Around wrapInner wrap wrapAll Replacing replaceWith, replaceAll Removing empty, remove Copying clone

14. Effects Basics show, hide, toggle Sliding slideUp, slideDown, slideToggle Fading fadeIn, fadeOut, fadeTo (opacity 0-1) Custom animate, stop

15. Plug-ins Extremely Simple – Promotes code reuse and DRY principle $.fn.MyPlugin = function(params) {}; Return a jQuery object to prevent from “breaking the chain” Unless you are returning a specific value Best Practice is to wrap the plug-in declaration within an anonymous JavaScript function in order to prevent collisions with the use of $ Within the plug-in ‘this’ refers to the jQuery object

16. AJAX Helpers load, get, getJSON, getScript, post (all use $.ajax behind the scenes) $.ajaxSetup(options) can be used to globally set the default options for all AJAX request. You can still override these within each AJAX request object. Local Events – subscribed to within AJAX request object Global Events – broadcast to all elements in the DOM Can be disabled within the AJAX request object’s ‘global’ property .bind(‘ajaxStart’, fn) or .ajaxStart(fn) G | ajaxStart L | beforeSend G | ajaxSend L | success G | ajaxSuccess L | error G | ajaxError L | complete G | ajaxComplete G | ajaxStop

17. Utility Functions Array and Object Operations $.each(object, callback) – Callback function will run for each item in the object. The each method is meant to be an immutable iterator and returns the original array. $.map(array, callback) – Callback function will run for each item in the array. The map method can be used as an iterator, but is designed to be used for manipulation of the supplied array and returns a new array. $.merge(first, second) – Merges the second array into the first array. $.unique(array) – Removes duplicate elements (only works on arrays of DOM elements). $.extend(object) – Add functions into the jQuery namespace. $.extend(deep, target, object1, objectN) – Merge values from objects 1 to N into target object. Deep is an optional boolean that if true, tells jQuery to do a deep copy. $.grep(array, callback, invert) – Iterates through array, and returns a new array with values from the original array that satisfy the criteria specified in the callback. $.inArray(value, array) – Gets the index of the value in the array (-1 if not found). String Operations $.trim(str) – Removes whitespace from the given string. Test Operations $.isArray(obj) – Determines if the object is an array. $.isFunction(obj) – Determines if the object is a function.

18. jQuery Data Can store data on one or more jQuery elements .data(name, value) value is an object Retrieves data from the first element in the jQuery object .data(name)

19. Resources jQuery Main http://jquery.com http://docs.jquery.com/Downloading_jQuery jQuery API Documentation http://api.jquery.com http://docs.jquery.com jQuery UI http://jqueryui.com http://jqueryui.com/themeroller/ jQuery Blog http://blog.jquery.com/ Around The Web http://stackoverflow.com http://www.nettuts.com http://www.smashingmagazine.com Tools Visual Studio JavaScript Intellisense Support (KB958502) http://getfirebug.com/ (Firebug Firefox Plug-in) http://jsbin.com/ (JS Bin - Collaborative JavaScript Debugging) Twitter @jquery, @jqueryui, @jresig, @rem, @codylindley , @reybango, @elijahmanor, @jamespadolsey, @brandonaaron, @malsup, @pbakaus, @rworth