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JQUERY SYNTAX

how to add  jQuery  to Your Web Pages ?:

There are several ways to start using jQuery on
your web site. You can:


(1)Download the jQuery library from jQuery.com


(2)Include jQuery from a CDN, like Google


Downloading jQuery :

There are two versions of jQuery available for downloading:

·         Production version - this is for your live website because
it has been minified and compressed
·         Development version - this is for testing and development
(uncompressed  and readable code)
Both versions can be downloaded from jQuery.com.

The jQuery  library is a single JavaScript file, and you reference it with the HTML<script>
tag (notice that the <script>  tag should be inside the <head> section):

<head>
<script  src="jquery-1.12.2.min.js"></script>
</head>
Tip: Place the downloaded file in the same directory as the pages where you wish to use it.
Note    Do you wonder why we do not have type="text/javascript" inside the <script> tag?

This is not required in HTML5. JavaScript is the default
 scripting language in HTML5 and in all modern browsers!

jQuery CDN :

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.

To use jQuery from Google or Microsoft, use one of the following:

Google CDN:
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.2/jquery.min.js"></script>
</head>
Try it Yourself »
Microsoft CDN:
<head>
<script src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.12.2.min.js"></script>

</head>




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)
Examples:

$(this).hide() - hides the current element.

$("p").hide() - hides all <p> elements.

$(".test").hide() - hides all elements with class="test".

$("#test").hide() - hides the element with id="test".


jQuery uses CSS syntax to select elements.
The Document Ready Event
You might have noticed that

 all jQuery methods in our examples, are inside a document ready event:

$(document).ready(function(){

   // jQuery methods go here...

});

This is 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. This also allows you to have your JavaScript code
 before the body of your document, in the head section.

Here are some examples of actions that can fail
 if methods are run before the document is fully loaded:

Trying to hide an element that is not created yet
Trying to get the size of an image that is not loaded yet
Tip: The jQuery  team has also created an even shorter method for the document ready event:

$(function(){

   // jQuery methods go here...


});
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