what’s the problem with javascript?

The magic of jQuery

Vlad AzarkhinSenior Architect & Technologist

Updated 23. february 2013 by Henrik Høltzer

What’s the problem with JavaScript?

JavaScript was a initially

introduced in Netscape 2.0B3

in Dec 1995,

a.k.a. Mocha, LiveScript, Jscript,

however, it’s official name is

ECMAScript

JavaScript is a C-family, world’s

worst named, extremely

powerful language (not a

script), totally unrelated to

Java

JavaScript is a weakly typed,

classless, prototype based OO

language, that can also be

used outside the browser. It is

not a browser DOM.

The world’s most

misunderstood

programming language.

(Douglas Crockford)

Browser DOM really sucks, and

this is where jQuery comes to

rescue.

This session is about improving your Quality of Life !

Introduction to jQuery

$(“#firstName”).text(“Joe Black”);

$(“button”).click(function() {alert

“Clicked”;});

$(“.content”).hide();

$(“#main”).load(“content.htm”);

$(“<div/

>”).html(“Loading…”).appendTo(“#content”);

$(“#firstName”).text(“Joe Black”);

$(“button”).click(function() {alert

“Clicked”;});

$(“.content”).hide();

$(“#main”).load(“content.htm”);

$(“<div/

>”).html(“Loading…”).appendTo(“#content”);

A Quality of Life by jQuery:

Very compact and fluent programming model

What is jQuery?

jQuery is a lightweight, open-

source JavaScript library that

simplifies interaction between

HTML and JavaScript

It was and still being

developed

by John Resig from

Mozilla and was first

announced in

January 2006

It has a great community, great

documentation, tons of

plugins, and also adopted by

Microsoft

The current version is 1.9.1

(as of february 2013)

http://blogs.microsoft.co.il/blogs/noam/jQuery8x6_7484FDCD.png

Getting Started

Download the latest version

from

http://jquery.com

http://jquery.com/

jquery.js should contain a copy of the compressed production code

<script src=“jquery.js”/><script src=“jquery.js”/>

Reference it in your markup

… or just drag it into the file

///<reference path=“jquery.js”/>///<reference

path=“jquery.js”/>

Reference it in your JS files:

jQuery Core Concepts

Create HTML elements on the fly

var el = $(“<div/>”)var el = $(“<div/>”)

The Magic $() function

Manipulate existing DOM elements

$(window).width()$(window).width()


Selects document elements

(more in a moment…)

$(“div”).hide();$(“div”).hide();


$(document).ready(function(){…});$(document).ready(function(){…});

Fired when the document is ready for programming.

Better use the full syntax:

$(function(){…});$(function(){…});


$(“div”).hide()

$(“<span/>”).appendTo(“body”)

$(“:button”).click()

$(“div”).hide()

$(“<span/>”).appendTo(“body”)

$(“:button”).click()

jQuery’s programming philosophy is:

GET >> ACT

$(“div”).show() .addClass(“main”) .html(“Hello jQuery”);

$(“div”).show() .addClass(“main”) .html(“Hello jQuery”);

Almost every function returns jQuery, which provides a fluent

programming interface and chainability:

Get > Act

Chainability

The $() function

Three Major Concepts of jQuery

jQuery Selectors

$(“*”) // find everything

$(“*”) // find everything

All Selector

Selectors return a pseudo-array of jQuery elements

$(“div”)

// <div>Hello jQuery</div>

$(“div”)

// <div>Hello jQuery</div>

Basic Selectors

Yes, jQuery implements CSS Selectors!

$(“#usr”)

// <span id=“usr”>John</span>

$(“#usr”)

// <span id=“usr”>John</span>

$(“.menu”)

// <ul class=“menu”>Home</ul>

$(“.menu”)

// <ul class=“menu”>Home</ul>

By Tag:

By ID:

By Class:

$(“div.main”) // tag and class

$(“table#data”) // tag and id

$(“div.main”) // tag and class

$(“table#data”) // tag and id

More Precise Selectors

// find by id + by class

$(“#content, .menu”)

// multiple combination

$(“h1, h2, h3, div.content”)

// find by id + by class

$(“#content, .menu”)

// multiple combination

$(“h1, h2, h3, div.content”)

Combination of Selectors

$(“table td”) // descendants

$(“tr > td”) // children

$(“label + input”) // next

$(“#content ~ div”) // siblings

$(“table td”) // descendants

$(“tr > td”) // children

$(“label + input”) // next

$(“#content ~ div”) // siblings

Hierarchy Selectors

$(“tr:first”) // first element

$(“tr:last”) // last element

$(“tr:lt(2)”) // index less than

$(“tr:gt(2)”) // index gr. than

$(“tr:eq(2)”) // index equals

$(“tr:first”) // first element

$(“tr:last”) // last element

$(“tr:lt(2)”) // index less than

$(“tr:gt(2)”) // index gr. than

$(“tr:eq(2)”) // index equals

Selection Index Filters

$(“div:visible”) // if visible

$(“div:hidden”) // if not

$(“div:visible”) // if visible

$(“div:hidden”) // if not

Visibility Filters

$(“div[id]”) // has attribute

$(“div[dir=‘rtl’]”) // equals to

$(“div[id^=‘main’]”) // starts with

$(“div[id$=‘name’]”) // ends with

$(“a[href*=‘msdn’]”) // contains

$(“div[id]”) // has attribute

$(“div[dir=‘rtl’]”) // equals to

$(“div[id^=‘main’]”) // starts with

$(“div[id$=‘name’]”) // ends with

$(“a[href*=‘msdn’]”) // contains

Attribute Filters

$(“input:checkbox”) // checkboxes

$(“input:radio”) // radio buttons

$(“:button”) // buttons

$(“:text”) // text inputs

$(“input:checkbox”) // checkboxes

$(“input:radio”) // radio buttons

$(“:button”) // buttons

$(“:text”) // text inputs

Forms Selectors

$(“input:checked”) // checked

$(“input:selected”) // selected

$(“input:enabled”) // enabled

$(“input:disabled”) // disabled

$(“input:checked”) // checked

$(“input:selected”) // selected

$(“input:enabled”) // enabled

$(“input:disabled”) // disabled

Forms Filters

$(“#cities option:selected”).val()

$(“#cities option:selected”).text()

$(“#cities option:selected”).val()

$(“#cities option:selected”).text()

Find Dropdown Selected Item

<select id=“cities”>

<option value=“1”>Tel-Aviv</option>

<option value=“2” selected=“selected”>Yavne</option>

<option value=“3”>Raanana</option>

</select>

<select id=“cities”>

<option value=“1”>Tel-Aviv</option>

<option value=“2” selected=“selected”>Yavne</option>

<option value=“3”>Raanana</option>

</select>

SELECTORS DEMO

Document Traversal

$(“div”).length$(“div”).length

Returns number of selected elements.

It is the best way to check selector.

A Selector returns a pseudo array of jQuery objects

$(“div”).get(2) or $(“div”)[2]$(“div”).get(2) or $(“div”)[2]

Returns a 2nd DOM element of the selection

Getting a specific DOM element

$(“div”).eq(2)$(“div”).eq(2)

Returns a 2nd jQuery element of the selection

Getting a specific jQuery element

var sum = 0;$(“div.number”).each(

function(){ sum += (+this.innerHTML);});

var sum = 0;$(“div.number”).each(

function(){ sum += (+this.innerHTML);});

this – is a current DOM element

each(fn) traverses every selected element calling fn()

$(“table tr”).each(function(i){

if (i % 2) $

(this).addClass(“odd”);});

$(“table tr”).each(function(i){

if (i % 2) $

(this).addClass(“odd”);});

$(this) – convert DOM to jQueryi - index of the current element

each(fn) also passes an indexer

.next(expr) // next sibling

.prev(expr) // previous sibling

.siblings(expr) // siblings

.children(expr) // children

.parent(expr) // parent

.next(expr) // next sibling

.prev(expr) // previous sibling

.siblings(expr) // siblings

.children(expr) // children

.parent(expr) // parent

Traversing HTML

$(“table td”).each(function() {if ($(this).is(“:first-

child”)) {$

(this).addClass(“firstCol”);}

});

$(“table td”).each(function() {if ($(this).is(“:first-

child”)) {$

(this).addClass(“firstCol”);}

});

Check for expression

// select paragraph and then find // elements with class ‘header’ inside $(“p”).find(“.header”).show();

// equivalent to:$(“.header”, $(“p”)).show();

// select paragraph and then find // elements with class ‘header’ inside $(“p”).find(“.header”).show();

// equivalent to:$(“.header”, $(“p”)).show();

Find in selected

$(“<li><span></span></li>”) // li.find(“span”) // span

.html(“About Us”) // span

.andSelf() // span, li.addClass(“menu”) //

span,li .end() // span

.end() // li

.appendTo(“ul.main-menu”);

$(“<li><span></span></li>”) // li.find(“span”) // span

.html(“About Us”) // span

.andSelf() // span, li.addClass(“menu”) //

span,li .end() // span

.end() // li

.appendTo(“ul.main-menu”);

Advanced Chaining

$(“div”).slice(2, 5).not(“.green”)

.addClass(“middle”);

$(“div”).slice(2, 5).not(“.green”)

.addClass(“middle”);

Get Part of Selected Result

HTML Manipulation

$(“p”).html(“<div>Hello $!</div>”);

// escape the content of div.b

$(“div.a”).text($(“div.b”).html());

$(“p”).html(“<div>Hello $!</div>”);

// escape the content of div.b

$(“div.a”).text($(“div.b”).html());

Getting and Setting Inner Content

// get the value of the checked checkbox$(“input:checkbox:checked”).val();

// get the value of the checked checkbox$(“input:checkbox:checked”).val();

Getting and Setting Values

// set the value of the textbox$(“:text[name=‘txt’]”).val(“Hello”);// set the value of the textbox$(“:text[name=‘txt’]”).val(“Hello”);

// select or check lists or checkboxes$(“#lst”).val([“NY”,”IL”,”NS”]);

// select or check lists or checkboxes$(“#lst”).val([“NY”,”IL”,”NS”]);

Handling CSS Classes// add and remove class$(“p”).removeClass(“blue”).addClass(“red”);

// add and remove class$(“p”).removeClass(“blue”).addClass(“red”);

// add if absent, remove otherwise$(“div”).toggleClass(“main”);// add if absent, remove otherwise$(“div”).toggleClass(“main”);

// test for class existance if ($(“div”).hasClass(“main”)) { //… }// test for class existance if ($(“div”).hasClass(“main”)) { //… }

// select > append to the end$(“h1”).append(“<li>Hello $!</li>”);

// select > append to the beginning$(“ul”).prepend(“<li>Hello $!</li>”);

// select > append to the end$(“h1”).append(“<li>Hello $!</li>”);

// select > append to the beginning$(“ul”).prepend(“<li>Hello $!</li>”);

Inserting new Elements

// create > append/prepend to selector$(“<li/>”).html(“9”).appendTo(“ul”);

$(“<li/>”).html(“1”).prependTo(“ul”);

// create > append/prepend to selector$(“<li/>”).html(“9”).appendTo(“ul”);

$(“<li/>”).html(“1”).prependTo(“ul”);

// select > replace$(“h1”).replaceWith(“<div>Hello</div>”);// select > replace$(“h1”).replaceWith(“<div>Hello</div>”);

Replacing Elements

// create > replace selection$(“<div>Hello</div>”).replaceAll(“h1”);// create > replace selection$(“<div>Hello</div>”).replaceAll(“h1”);

$(“h3”).each(function(){$(this).replaceWith(“<div>”

+ $(this).html() + ”</div>”);

});

$(“h3”).each(function(){$(this).replaceWith(“<div>”

+ $(this).html() + ”</div>”);

});

Replacing Elements while keeping the content

// remove all children$(“#mainContent”).empty();// remove all children$(“#mainContent”).empty();

Deleting Elements

// remove selection$(“span.names”).remove();// remove selection$(“span.names”).remove();

// change position$(“p”).remove(“:not(.red)”)

.appendTo(“#main”);

// change position$(“p”).remove(“:not(.red)”)

.appendTo(“#main”);

$(“a”).attr(“href”,”home.htm”);// <a href=“home.htm”>…</a>$(“a”).attr(“href”,”home.htm”);// <a href=“home.htm”>…</a>

Handling attributes

// set the same as the first one$(“button:gt(0)”).attr(“disabled”,

$(“button:eq(0)”).attr(“disabled));

// set the same as the first one$(“button:gt(0)”).attr(“disabled”,

$(“button:eq(0)”).attr(“disabled));

// remove attribute - enable$(“button”).removeAttr(“disabled”)// remove attribute - enable$(“button”).removeAttr(“disabled”)

$(“img”).attr({“src” :

“/images/smile.jpg”,“alt” : “Smile”,“width” : 10,“height” : 10

});

$(“img”).attr({“src” :

“/images/smile.jpg”,“alt” : “Smile”,“width” : 10,“height” : 10

});

Setting multiple attributes

// get style$(“div”).css(“background-color”);// get style$(“div”).css(“background-color”);

CSS Manipulations

// set style $(“div”).css(“float”, “left”);// set style $(“div”).css(“float”, “left”);

// set multiple style properties$(“div”).css({“color”:”blue”,

“padding”: “1em” “margin-right”: “0”, marginLeft: “10px”});

// set multiple style properties$(“div”).css({“color”:”blue”,

“padding”: “1em” “margin-right”: “0”, marginLeft: “10px”});

// get window heightvar winHeight = $(window).height();

// set element height$(“#main”).height(winHeight);

//.width() – element

//.innerWidth() – .width() + padding

//.outerWidth() – .innerWidth() + border

//.outerWidth(true) – including margin

// get window heightvar winHeight = $(window).height();

// set element height$(“#main”).height(winHeight);

//.width() – element

//.innerWidth() – .width() + padding

//.outerWidth() – .innerWidth() + border

//.outerWidth(true) – including margin

Dimensions

The default unit is Pixel (px)

// from the document$(“div”).offset().top;

// from the parent element$(“div”).position().left;

// scrolling position$(window).scrollTop();

// from the document$(“div”).offset().top;

// from the parent element$(“div”).position().left;

// scrolling position$(window).scrollTop();

Positioning

Events

$(document).ready(function(){//…

});

$(document).ready(function(){//…

});

When the DOM is ready…

Fires when the document is ready for programming.

Uses advanced listeners for detecting.

window.onload() is a fallback.

// execute always$(“div”).bind(“click”, fn);

// execute only once$(“div”).one(“click”, fn);

// execute always$(“div”).bind(“click”, fn);

// execute only once$(“div”).one(“click”, fn);

Attach Event

Possible event values: blur, focus, load, resize, scroll, unload, beforeunload,

click, dblclick, mousedown, mouseup, mousemove, mouseover, mouseout, mouseenter, mouseleave,

change, select, submit, keydown, keypress, keyup, error

(or any custom event)

jQuery.Event object

$(“div”).unbind(“click”, fn);$(“div”).unbind(“click”, fn);

Detaching Events

(Unique ID added to every attached function)

$(“div”).trigger(“click”);$(“div”).trigger(“click”);

Events Triggering

Triggers browser’s event action as well.

Can trigger custom events.

Triggered events bubble up.

// attach / trigger

elem.blur(fn) / elem.blur()

elem.focus(fn) / elem.focus()

elem.click(fn) / elem.click()

elem.change(fn) / elem.change()

// attach / trigger

elem.blur(fn) / elem.blur()

elem.focus(fn) / elem.focus()

elem.click(fn) / elem.click()

elem.change(fn) / elem.change()

Events Helpers

And many others…

// use different triggering function$(“div”).triggerHandler(“click”);// use different triggering function$(“div”).triggerHandler(“click”);

Preventing Browser Default Action

// prevent default action in handlerfunction clickHandler(e) {

e.preventDefault();}

// prevent default action in handlerfunction clickHandler(e) {

e.preventDefault();}

// or just return falsefunction clickHandler(e) {return false;}// or just return falsefunction clickHandler(e) {return false;}

// stop bubbling, keep other handlerfunction clickHandler(e) {

e.stopPropagation();}

// stop bubbling, keep other handlerfunction clickHandler(e) {

e.stopPropagation();}

Preventing Bubbling

// stop bubbling and other handlersfunction clickHandler(e) {

e.stopImmediatePropagation();}

// stop bubbling and other handlersfunction clickHandler(e) {

e.stopImmediatePropagation();}

// or just return falsefunction clickHandler(e) {return false;}// or just return falsefunction clickHandler(e) {return false;}

// attach live event(“div”).live(“click”, fn);

// detach live event(“div”).die(“click”, fn);

// attach live event(“div”).live(“click”, fn);

// detach live event(“div”).die(“click”, fn);

Live Events

Currently supported events:click, dblclick, mousedown, mouseup, mousemove, mouseover, mouseout, keydown, keypress, keyup

EVENTS DEMO

Effects

// just show$(“div”).show();

// reveal slowly, slow=600ms$(“div”).show(“slow”);

// hide fast, fast=200ms$(“div”).hide(“fast”);

// hide or show in 100ms $(“div”).toggle(100);

// just show$(“div”).show();

// reveal slowly, slow=600ms$(“div”).show(“slow”);

// hide fast, fast=200ms$(“div”).hide(“fast”);

// hide or show in 100ms $(“div”).toggle(100);

Showing or Hiding Element

$(“div”).slideUp();

$(“div”).slideDown(“fast”);

$(“div”).slideToggle(1000);

$(“div”).slideUp();

$(“div”).slideDown(“fast”);

$(“div”).slideToggle(1000);

Sliding Elements

$(“div”).fadeIn(“fast”);

$(“div”).fadeOut(“normal”);

// fade to a custom opacity$(“div”).fadeTo (“fast”, 0.5);

$(“div”).fadeIn(“fast”);

$(“div”).fadeOut(“normal”);

// fade to a custom opacity$(“div”).fadeTo (“fast”, 0.5);

Fading Elements

Fading === changing opacity

$(“div”).hide(“slow”, function() {alert(“The DIV is hidden”);

});

$(“div”).show(“fast”, function() {$(this).html(“Hello jQuery”);

}); // this is a current DOM element

$(“div”).hide(“slow”, function() {alert(“The DIV is hidden”);

});

$(“div”).show(“fast”, function() {$(this).html(“Hello jQuery”);

}); // this is a current DOM element

Detecting animation completion

Every effect function has a (speed, callback) overload

// .animate(options, duration)$(“div”).animate({

width: “90%”,opacity: 0.5,borderWidth:

“5px”

}, 1000);

// .animate(options, duration)$(“div”).animate({

width: “90%”,opacity: 0.5,borderWidth:

“5px”

}, 1000);

Custom Animation

$(“div”).animate({width: “90%”},100).animate({opacity: 0.5},200).animate({borderWidth:

“5px”});

$(“div”).animate({width: “90%”},100).animate({opacity: 0.5},200).animate({borderWidth:

“5px”});

Chaining Animation

By default animations are queued and than performed one by one

$(“div”).animate({width: “90%”},

{queue:false, duration:1000})

.animate({opacity : 0.5});

$(“div”).animate({width: “90%”},

{queue:false, duration:1000})

.animate({opacity : 0.5});

Controlling Animations Sync

The first animation will be performed immediately without queuing

EFFECTS DEMO

AJAX with jQuery

$(“div”).load(“content.htm”);

// passing parameters$(“#content”).load(“getcontent.aspx”,

{“id”:”33”,

“type”:”main”});

$(“div”).load(“content.htm”);

// passing parameters$(“#content”).load(“getcontent.aspx”,

{“id”:”33”,

“type”:”main”});

Loading content

$.get(“test.aspx”, {id:1},function(data)

{alert(data);});

$.post(“test.aspx”, {id:1},function(data)

{alert(data);});

$.get(“test.aspx”, {id:1},function(data)

{alert(data);});

$.post(“test.aspx”, {id:1},function(data)

{alert(data);});

Sending GET/POST requests

$.getJSON(“users.aspx”, {id:1},function(users){

alert(users[0].name);});

$.getJSON(“users.aspx”, {id:1},function(users){

alert(users[0].name);});

Retrieving JSON Data

$.getScript(“script.js”,function(){

doSomeFunction();});

$.getScript(“script.js”,function(){

doSomeFunction();});

Retrieving JS Files

AJAX DEMO

Extending the Library

// definitionjQuery.fn.printLine = function(s) {

return jQuery(this).each(function() { this.append(“<div>”+ s +“</div>”);

});};

// usage$(“#log”).printLine(“Hello”);

// definitionjQuery.fn.printLine = function(s) {

return jQuery(this).each(function() { this.append(“<div>”+ s +“</div>”);

});};

// usage$(“#log”).printLine(“Hello”);

Adding Methods

Do not use $ in the method (at least not until next slide)

$.expr[‘:’].test = function(o, i, m, s) {

// o – current object in the selection

// i – loop index in the stack

// m – meta data about your selector

// s – stack of all the elements

// return true to include the element

// return false to exclude the element

};

$.expr[‘:’].test = function(o, i, m, s) {

// o – current object in the selection

// i – loop index in the stack

// m – meta data about your selector

// s – stack of all the elements

// return true to include the element

// return false to exclude the element

};

Custom Selectors

LIBRARY EXTENSION DEMO

More Functionality on every aspect

URL parameters parser

Browser and features detection

Data Cache

Utilities Helper functions

Various Plug-ins

More things to explore

jQuery web-site: http://jquery.com

jQuery API: http://api.jquery.com

Many many blogs

jQuery in Action book:

Where to go next

http://jquery.com/

http://api.jquery.com/

what’s the problem with javascript?

Documents

css selectors

label input

tr td children

widththe magic

hidethe magic

idmore precise selectors

fluent programming modelwhat

fluent programming interface