jQuery Presentasion

jQuery
Mohammad Usman
Salesforce Consultant & Architect

What is jQuery?
• A cross-browser library of JavaScript functions.
• 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
• Features
• Select and manipulate HTML
• Manipulate CSS
• JavaScript Effects and animations
• HTML DOM traversal and modification
• AJAX

How jQuery Works
• The jQuery syntax is used to select HTML elements and
perform some action on those element(s).
• Basic syntax is: $(selector).action()
• A dollar sign to define jQuery
• A (selector) to find HTML elements
• An action() to be performed on the element(s)

Getting Started
• Download jQuery
• http://code.jquery.com/jquery-latest-version.js
• Rename to jquery-versionName.js
• Save
• Put it in Static Resources
• Create a test page “JquerySelectorExample”
• Edit the src/value attribute in the script tag
• Register a ready event

OR
<script src=“jquery.js”/>
Reference it in your markup
<apex:includeScript value=
“{!$Resource.jqueryVersion}”/>

Create HTML elements on the fly
var el = $(“<div/>”)
The Magic $() function

Manipulate existing DOM elements
$(window).width()

Selects document elements
(more in a moment…)
$(“div”).hide();
$(“div”, $(“p”)).hide();

$(document).ready(function(){…});
Fired when the document is ready for
programming.
Better use the full syntax:
$(function(){…});

It may be used in case of conflict with other
frameworks.
jQuery(“div”);
The full name of $() function is

jQuery uses closures for isolation
(function(){
var
jQuery=window.jQuery=window.$=function(){
// …
};
})();
The library is designed to be isolated

var f$ = jQuery.noConflict();
// now foo() is the jQuery main function
f$(“div”).hide();
Avoid $() conflict with other frameworks
// remove the conflicting $ and jQuery
var f$ = jQuery.noConflict(true);

$(“div”).hide()
$(“span”).appendTo(“body”)
$(“:button”).click()
jQuery’s programming philosophy is:
GET >> ACT

$(“div”).show()
.addClass(“main”)
.html(“Hello jQuery”);
Almost every function returns jQuery,
which provides a fluent programming
interface and chainability:

Comparison
• Compare the following:
What are the
advantages
of the jQuery
method?
$("a").click(function(){
alert("You clicked a link!");
});
<a href="" onclick="alert(‘You clicked a link!')">Link</a>

Get > Act
Chainability
The $() function
Three Major Concepts of jQuery

$(“*”) // find everything
All Selector
Selectors return a pseudo-array of jQuery
elements

$(“div”)
// <div>Hello jQuery</div>
Basic Selectors
Yes, jQuery implements CSS Selectors!
$(“#usr”)
// <span id=“usr”>John</span>
$(“.menu”)
// <ul class=“menu”>Home</ul>
By Tag:
By ID:
By Class:

$(“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”)
Combination of Selectors

$(“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
Selection Index Filters

$(“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
Attribute Filters

$(“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
Forms Filters

$(“select[name=‘ddl’] option:selected”).val()
Find Dropdown Selected Item
<select name=“cities”>
<option value=“1”>Tel-Aviv</option>
<option value=“2” selected=“selected”>Yavne</option>
<option value=“3”>Raanana</option>
</select>

Examples
$("button").click(function(){
alert($("p").css("color"));
});
$("p").css({
"color":"white",
"background-color":"#98bf21",
"font-family":"Arial",
"font-size":"20px",
"padding":"5px"
});
});
alert($("p").css("color"));
});

Challenge
• Highlight (background-color = yellow) any paragraph that
is double-clicked
<script>
$(document).ready(function(){
$("p").dblclick(function(){
$(this).css("background-color", "yellow");
});
});
</script>

$(“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]
Returns a 2nd DOM element of the selection
Getting a specific DOM element

$(“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);
});
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”);
});
$(this) – convert DOM to jQuery
i - 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
Traversing HTML

$(“table td”).each(function() {
if ($(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();
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”);
Advanced Chaining

$(“div”)
.slice(2, 5)
.not(“.green”)
.addClass(“middle”);
Get Part of Selected Result

$(“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();
Getting and Setting Values
// set the value of the textbox
$(“:text[name=‘txt’]”).val(“Hello”);
// select or check lists or checkboxes
$(“#lst”).val([“NY”,”IL”,”NS”]);

Handling CSS Classes
// add and remove class
$(“p”).removeClass(“blue”).addClass(“red”);
// add if absent, remove otherwise
$(“div”).toggleClass(“main”);
// test for class existance
if ($(“div”).hasClass(“main”)) { //… }

// select > append to the end
$(“h1”).append(“<li>Hello $!</li>”);
// select > append to the beginning
$(“ul”).prepend(“<li>Hello $!</li>”);
Inserting new Elements
// create > append/prepend to selector
$(“<li/>”).html(“9”).appendTo(“ul”);
$(“<li/>”).html(“1”).prependTo(“ul”);

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

$(“h3”).each(function(){
$(this).replaceWith(“<div>”
+ $(this).html()
+ ”</div>”);
});
Replacing Elements while keeping the
content

// remove all children
$(“#mainContent”).empty();
Deleting Elements
// remove selection
$(“span.names”).remove();
// change position
$(“p”).remove(“:not(.red)”)
.appendTo(“#main”);

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

$(“img”).attr({
“src” : “/images/smile.jpg”,
“alt” : “Smile”,
“width” : 10,
“height” : 10
});
Setting multiple attributes

// get style
$(“div”).css(“background-color”);
CSS Manipulations
// set style
$(“div”).css(“float”, “left”);
// set multiple style properties
$(“div”).css({“color”:”blue”,
“padding”: “1em”
“margin-right”: “0”,
marginLeft: “10px”});

// get window height
var 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();
Positioning

$(document).ready(function(){
//…
});
When the DOM is ready…
• The document.ready() function executes when the
document is finished loading
• Defining jQuery functions inside document.ready()
prevents them from executing prematurely
• 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);
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)

$(“div”).unbind(“click”, fn);
Detaching Events
(Unique ID added to every attached function)

$(“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()
Events Helpers
And many others…

// use different triggering function
$(“div”).triggerHandler(“click”);
Preventing Browser Default Action
// prevent default action in handler
function clickHandler(e) {
e.preventDefault();
}
// or just return false
function clickHandler(e) {return false;}

// stop bubbling, keep other handler
e.stopPropagation();
}
Preventing Bubbling
// stop bubbling and other handlers
e.stopImmediatePropagation();
}
// or just return false
function clickHandler(e) {return false;}

// 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

// 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);
Sliding Elements

$(“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
Detecting animation completion
Every effect function has a (speed, callback)
overload

// .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”});
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});
Controlling Animations Sync
The first animation will be performed
immediately without queuing

// definition
jQuery.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)

(function ($) {
jQuery.fn.printLine = function(s) {
return $(this).each(function() {
this.append(“<div>”+ s +“</div>”);
});
};
})(jQuery);
Closure to solve the $ issue

$.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

Resources
• http://jquery.com/
• http://www.w3schools.com/jquery
• http://jqueryui.com/
• http://jquery.somee.com/
• Check out the demos and learn!

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