Understanding JQuery for web development by software outsourcing company india

 jQuery is a JavaScript Library.
 jQuery greatly simplifies JavaScript programming.
 jQuery is a lightweight, "write less, do more", JavaScript library.
 jQuery simplifies HTML document traversing, event handling, animating, and
Ajax interactions for rapid web development.
 The purpose of jQuery is to make it much easier to use JavaScript on your
website.
Introduction to JQuery
Custom Online Shop Developershttp://www.ifourtechnolab.com

 There are lots of other JavaScript frameworks out there, but jQuery seems to be
the most popular, and also the most extendable.
 Many of the biggest companies on the Web use jQuery, such as:
• Google
• Microsoft
• IBM
• Netflix
Advantages of jQuery

 There are several ways to start using jQuery on your web site.
• Download the jQuery library from jQuery.com
• Include jQuery from a CDN, like Google
 There are two versions of jQuery available for downloading:
• Production version
• Development version
 If you don't want to download and host jQuery yourself, you can include it from a
CDN (Content Delivery Network).
 Both Google and Microsoft host jQuery.
How to Install

jQuery Syntax
 The jQuery syntax is tailor made for selecting HTML elements and performing
some action on the element(s).
 Basic syntax is: $(selector).action().
• A $ sign to define/access jQuery.
• A (selector) to "query (or find)" HTML elements.
• A jQuery action() to be performed on the element(s).
 The Document Ready event is used to prevent any jQuery code from running
before the document is finished loading (is ready).
 It is good practice to wait for the document to be fully loaded and ready before
working with it.

Enable jQuery in your page
• jQuery can be enabled in your page by including
reference to jQuery library file
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js">
• Introduce a jQuery function by using the below below given function.
$(document).ready(function(){
//Script goes here
});
OR
$(function(){
//Script goes here
});

JavaScript vs jQuery
• Example 1 - Hide an element with id "textbox“
//javascript
document.getElementById('textbox').style.display = "none";
//jQuery
$(' #textbox' ).hide();
• Example 2 - Create a <h1> tag with "my text“
//javascript
var h1 = document.CreateElement("h1");
h1.innerHTML = "my text";
document.getElementsByTagName('body')[0].appendChild(h1);
//jQuery
$(' body').append( $("<h1/>").html("my text") ;

 jQuery selectors are one of the most important parts of the jQuery library.
 jQuery selectors allow you to select and manipulate HTML element(s).
 jQuery selectors are used to "find" (or select) HTML elements based on their
id, classes, types, attributes, values of attributes and much more.
 The jQuery element selector selects elements based on the element name.
 The jQuery #id selector uses the id attribute of an HTML tag to find the
specific element.
 The jQuery class selector finds elements with a specific class.
jQuery Selectors

Basic selectors
• TagName
document.getElementsByTagName("tagName"); (javascript)
$("tagName") - $("div"), $("p"), $("div"),.....
• Tag ID
document.getElementById("id"); (javascript)
$("#id") - $("#name"), $("#address")
• Tag Class
document.getElementsByClassName("className"); (javascript)
$(".className") - $(".comment"), $(".code")
• To select all elements - $("*")

Positional Selectors
Syntax: Examples:
$("selector:first") $("p:first")
$("selector:last") $("p:last")
$("selector:odd") $("p:odd")
$("selector:even") $("p:even")
$("selector:eq(i)") $("p:eq(1)")
$("selector:gt(i)") $("p:gt(1)")
$("selector:lt(i)") $("p:lt(1)")

Form Element(Custom) Selectors
$("selector:visible") $("selector:input")
$("selector:hidden") $("selector:text")
$("selector:disabled") $("selector:password")
$("selector:enabled") $("selector:radio")
$("selector:checked") $("selector:checkbox")
$("selector:selected") $("selector:submit")
$("selector:header") $("selector:reset")
$("selector:animated") $("selector:image")
$("selector:not(selector:not)") $("selector:file")
$("selector:button")

Retrieve, Set and Remove attribute
Syntax: Examples:
• $("selector").attr("name") • $("img").attr("src")
• $("selector").attr("key","val") • $("p").attr("class","source")
• $("selector").attr("key",fn()) • $("img").attr("height",calHt())
• $("selector").attr(properties) • $("img").attr({"src":"/path/","title" : "My Img"});
• $("selector").removeAttr(attr) • $("div").removeAttr("class“)

Class, HTML, Text, Value - Functions
• $("selector").hasClass("className")
• $("selector").addClass("className")
• $("selector").removeClass("className")
• $("selector").toggleClass("className")
• $("selector").html()
• $("selector").html("html code")
• $("selector").text()
• $("selector").text("text content")
• $("selector").val()
• $("selector").val("value")

 All the different visitor's actions that a web page can respond to are called events.
 An event represents the precise moment when something happens.
 Examples:
• moving a mouse over an element
• selecting a radio button
• clicking on an element
 The term "fires/fired" is often used with events. Example: "The keypress event is
fired, the moment you press a key".
Events

Commonly Used jQuery Event Methods
 click()
• The click() method attaches an event handler function to an HTML
element.
• The function is executed when the user clicks on the HTML element.
• The following example says: When a click event fires on a <p> element;
hide the current <p> element:
• Example: $("p").click(function(){
$(this).hide();
});

 dblclick()
• The dblclick() method attaches an event handler function to an HTML
element.
• The function is executed when the user double-clicks on the HTML
element:
• Example: $("p").dblclick(function(){
$(this).hide();
});

 mouseenter()
• The mouseenter() method attaches an event handler function to an
HTML element.
• The function is executed when the mouse pointer enters the HTML
element:
• Example: $("#p1").mouseenter(function(){
alert("You entered p1!");
});

 mouseleave()
• The mouseleave() method attaches an event handler function to an
HTML element.
• The function is executed when the mouse pointer leaves the HTML
element:
• Example: $("#p1").mouseleave(function(){
alert("Bye! You now leave p1!");
});

 mousedown()
• The mousedown() method attaches an event handler function to an
HTML element.
• The function is executed, when the left, middle or right mouse button is
pressed down, while the mouse is over the HTML element:
• Example: $("#p1").mousedown(function(){
alert("Mouse down over p1!");
});

 mouseup()
• The mouseup() method attaches an event handler function to an HTML
element.
• The function is executed, when the left, middle or right mouse button is
released, while the mouse is over the HTML element:
• Example: $("#p1").mouseup(function(){
alert("Mouse up over p1!");
});

 hover()
• The hover() method takes two functions and is a combination of the
mouseenter() and mouseleave() methods.
• The first function is executed when the mouse enters the HTML element,
and the second function is executed when the mouse leaves the HTML
element:
• Example: $("#p1").hover(function(){
alert("You hover p1!");
});

 focus()
• The focus() method attaches an event handler function to an HTML form
field.
• The function is executed when the form field gets focus:
• Example: $("input").focus(function(){
$(this).css("background-color", "#cccccc");
});

 blur()
• The blur() method attaches an event handler function to an HTML form
field.
• The function is executed when the form field loses focus:
• Example: $("input").blur(function(){
$(this).css("background-color", "#ffffff");
});

Useful Event Functions
 .hide() display:true
 .show() display:none
 .toggle(func1, func2) first click calls func1, next click
executes func2
 .hover(over, out) mouseover, mouseout

Effects
• show()
Shows the selected elements
• Hide()
Hides the selected elements
• fadeIn()
Fades in the selected elements
• fadeOut()
Fades out the selected elements
• fadeToggle()
Toggles between the fadeIn() and fadeOut() methods
• slideUp()
Slides-up (hides) the selected elements

 slideDown()
Slides-down (shows) the selected elements
 Finish()
Stops, removes and completes all queued animations for the selected elements
 Delay()
Sets a delay for all queued functions on the selected elements
 Animate()
Runs a custom animation on the selected elements
 Stop()
Stops the currently running animation for the selected elements
 Dequeue()
Removes the next function from the queue, and then executes the function
Effects

Thank you
Software development company indiahttp://www.ifourtechnolab.com

Understanding JQuery for web development by software outsourcing company india

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