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Introduction to jQuery

Introduction to jQuery. jQuery Quick facts. Is a cross-compatible javascript library Released in 2006 by John Resig Simplifies HTML document traversing, event handling, animating, and AJAX. Write less, do more!. Disclaimer!.

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Introduction to jQuery

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  1. Introduction to jQuery

  2. jQuery Quick facts • Is a cross-compatible javascript library • Released in 2006 by John Resig • Simplifies HTML document traversing, event handling, animating, and AJAX. • Write less, do more!

  3. Disclaimer! • No lecture, tutorial, or video will be able to give you all possible information about jQuery. • You MUST visit the jQuery API website to find extensive documentation and some examples for learning all the ins/outs of jQuery. CSE 3345

  4. Getting jQuery • You can download and locally host a copy which can be downloaded here. • Hotlink Google’s copy which is available here. • I prefer hot linking to Google’s copy. CSE 3345

  5. Including jQuery in web pages • To include jQuery in your website, all you need is a script tag with its srcpointed to the hosted location. <scriptsrc="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"> </script> CSE 3345

  6. Using jQuery • To use the jQuery library in your javascript, you can either use the jQuery() function or more simply the $(). • $() creates a jQuery object CSE 3345

  7. window.onload • Previously, we used the window.onload event as the place to start using javascript that manipulates the HTML document. • We used the window.onload event because that gets fired when all the objects in the document have been loaded into the DOM and all the images have finished loading. CSE 3345

  8. .ready() event • jQuery provides a simple statement that checks the document and waits until it’s ready to be manipulated called the ready event. • You’ll put most of your code in this method $(document).ready(function(){ // Your code here }); CSE 3345

  9. Get some Elements • jQuery provides two approaches to select elements: • jQuery Selectors • jQuery Filter Methods • Both approaches return a jQuery object which contains an array of all elements found. CSE 3345

  10. jQuery Selectors Supports CSS selectors versions 1-3 • By element: $(“div”) • By id : $(“#id”) • By class: $(“.classname”) • By attribute: $(“a[href]”) • By attribute that contains value: $(“div[class*=‘warning’]”) • Any CSS selector will work CSE 3345

  11. jQuery selectors • See here for complete list. CSE 3345

  12. Your turn <html> <head><title>Quiz</title></html> <body> <divid="nav"> <ahref="http://www.google.com">Google</a> <ahref="http://www.bing.com">Bing</a> <pclass="warning">You should be careful!! jQuery is super powerful and may be harmful to small babies</p> </div> </body> </html> -Select the google anchor element ( I can think of 5 ways to do this) -Select the element with an id equal to nav -Select the element with the class equal to warning CSE 3345

  13. jQuery Example Link • http://jsfiddle.net/blinkmacalahan/UYANa/ CSE 3345

  14. jQuery Filter Methods • jQuery provides methods that will ‘filter’ sets return from a selector search. • .first() – reduces a set of matched elements to the first item • .last() – reduces a set of matched elements to the last item • .eq(index) – reduces a set of matched elements to the one at the specified index • .slice( start [, end] ) - reduces a set of matched elements to the subset specified by the range of indices • .find(selector|jQueryObject|element) –search the descendants of the current set filtered by a selector, jQuery Object, or element. CSE 3345

  15. jQuery Object • $(‘div’) will return a jQuery Object that contains an array of matched elements for the specified selector. • Using that jQuery object, we can perform any jQuery method on that object. CSE 3345

  16. jQuery Method Examples $("div").find("a"); $("body *").first(); $("body *").last(); $("body > *").slice(0,2);//selects the first two children of the body element CSE 3345

  17. CSS Methods • .addClass() – Adds the specified class(es) to each element of the matched set. • .hasClass() - Determine whether any of the matched elements are assigned the given class. • .removeClass() -Remove a single class, multiple classes, or all classes from each element in the set of matched elements. CSE 3345

  18. CSS Methods .addClass("warning");//adds the warning class .addClass("warning critical");//adds the warning & critical classes .hasClass("warning");// returns true .hasClass("penguin");// returns false .removeClass("warning");//remove the warning class .removeClass("warning critical");//remove the warning & critical classes .removeClass();//removes all classes CSE 3345

  19. CSS Method .height() • Gets the current computed height for the first element’s content area of the matched set. • Returns a unit-less numeric pixel value (No parseInt() required). • Recommended for math calculations CSE 3345

  20. CSS Method .height(value) • Sets the CSS height of every element in the matched set • value can be an integer representing a number • value can be a String but it must include valid units CSE 3345

  21. .height() example $(window).height();//685 $('div').height();// 50 $('div').eq(0).height(100);//sets the height of the first div element of the matched set to 100px $('div').eq(0).height("100px");//same as previous statement CSE 3345

  22. Other CSS height Methods • .innerHeight() – get the height of the element including padding. • .outerHeight(includeMargin) – get the height of the element including padding, border, and optionally margin. CSE 3345

  23. CSS Method .width() • Exactly like .height(), but using width CSE 3345

  24. CSS Element Coordinate Methods • .offset() – returns the current coordinates of the first element in the matched set relative to the document. • .position() - returns the current coordinates of the first element in the matched set relative to the elements containing block. CSE 3345

  25. CSS Methods .css() • .css() – Get the value of a style property for the first element in the set of matched elements. • .css(propertyName, value) – set one or more CSS properties for the matched set. • Get/set any CSS 1 & 2 property. Some of CSS3 isn’t supported by vanilla jQuery, but plugins can be used to support them. CSE 3345

  26. .css() examples $('p').css('height');// "50px" $('p').css('color');// "rgb(255, 255, 255)" $('p').css('width','100px');//sets the matched elements' width to 100px $('p:last').css('color','red');//sets the last item of the matched elements color to red CSE 3345

  27. Mixing jQuery and DOM API • Using the jQuery object of matched elements, we can access a particular element using array index notation. • Doing this will return a DOM node. // returns a DOM node for the first matched element $('div')[0]; CSE 3345

  28. Mixing jQuery and DOM API • You CAN’T use jQuery methods directly on a DOM node. $('div')[0].css('color','red');//this WON'T work $('div')[2].height();//this WON'T work CSE 3345

  29. Mixing jQuery and DOM API • You CAN use DOM API properties and methods on DOM nodes directly. //The following uses DOM API properties on DOM nodes $('div')[0].style.color;// "red" $('div')[0].style.display;// "block" //The following uses DOM API methods on DOM nodes $('div')[0].addEventListener('click',function(e){ alert(e.target);},false); CSE 3345

  30. Mixing jQuery and DOM API • If you have a DOM node and want to use jQuery on it, use the node as the selector. //This example is a little wasteful var node = $('div')[0]; $(node).css('color');// "black" //This example is useful $(document.body).css('display');// "block" CSE 3345

  31. jQuery Events CSE 3345

  32. Subset of jQuery Events • .click() • .dblclick() • .focus(), .focusin(), .focusout() • .hover() • .keydown(), .keyup(), .keypress() • .mousedown(), .mouseup() • .mousemove() • .ready() CSE 3345

  33. .hover() • Binds two event handlers to the set of matched elements. • One handler is executed when the mouse pointer enters an element. • A second handler is executed when the point leaves the element. CSE 3345

  34. .hover() example • http://jsfiddle.net/blinkmacalahan/M5Ccz/ CSE 3345

  35. Ways to use .hover() • Fade in/out objects • Make elements grow/shrink • Change element’s class and take advantage of CSS CSE 3345

  36. .ready() • Unlike the window.onload event, jQuery’sready() is handled once the DOM hierarchy has been fully constructed. • In most cases, this is the best place to attach jQuery event handlers or run other jQuery code. • However if you need to perform operations on images, you’ll need to use jQuery’sload() event. CSE 3345

  37. .css() revisited • Using .css() as a setter method only modifies the element’s inline style. • You can unset an applied inline styles by supplying an empty string a the property value. • Note this does NOT remove a style that has been applied with a CSS rule in a stylesheet or <style> element. CSE 3345

  38. Unsetting inline CSS property //this removes any inline color style applied $('div:first').css('color',''); CSE 3345

  39. .css() revisited • jQuery can equally interpret CSS and DOM style properties. • So the following sets are equivalent: $('div').css('background-color','red'); $('div').css('backgroundColor','red'); $('div').css('margin-top');// 100px $('div').css('marginTop');//100px CSE 3345

  40. .css() revisited • If you dislike having to set CSS properties one at a time, then you’re in luck. • You can pass a JSON string which consists of property-value pairs to set multiple CSS properties. CSE 3345

  41. .css() with JSON //sets the bg color to black and the color to red all in one //method call $('div').css({'background-color':'black','color':'red'}); $('span').css({'position':'absolute','top':'10px','left':'200px'}); CSE 3345

  42. jQuery Effects CSE 3345

  43. jQuery Effects • The jQuery library provides several techniques for adding animations to a webpage. • You can create custom animations • You can use standard pre-made animations CSE 3345

  44. Premade Fade Animations • .fadeIn() - display matched elements by fading them to opaque. • .fadeOut() – display matched elements by fading them to transparent. • .fadeTo() – adjust the opacity of matched elements. CSE 3345

  45. .fadeIn() • .fadeIn() – animates matched elements to opaque over 400ms. • .fadeIn([duration]) – animates matched elements to opaque over duration ms. • You can use the string fast and slow to indicate durations of 200 and 600ms. CSE 3345

  46. .fadeIn() • .fadeIn([callback]) – you can provide a function to call once the animation is complete. • Using the .fadeIn() method on an element with display: none will change the element’s display value to inline or block. CSE 3345

  47. .fadeIn() Example //fades matched img element to opaque after 400ms $('img').fadeIn(); //fades matched img elements to opaque after 200ms; $('img').fadeIn('fast'); $('img').fadeIn(100,function(){ alert('~100ms have elapsed since click'); }); CSE 3345

  48. .fadeOut() • Very similar to fadeIn() except for the following: • Matched elements fade to transparent • At the end of the animation, the element’s display property is set to none. CSE 3345

  49. .fadeOut() Example $('img').fadeOut(100,function(){ alert("The element's display property value is now none"); }); CSE 3345

  50. Premade hiding/showing animations • .hide() – Hide the matched elements • .show() – Display the matched elements CSE 3345

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