What is jQuery?

jQuery  is “write less, do more” open source Javascript library.

Specialized for changing web page documents on the fly.

jQuery makes it easy to add action and interactivity to any web page.

jQuery makes things like HTML document traversal and manipulation, event handling, animation, and Ajax much simpler with an easy-to-use API that works across a multitude of browsers.

jQuery is the core library. jQueryUI is built on top of it. If you use jQueryUI, you must also include jQuery.

Importance of  jQuery?

Open Source.

jQuery is SEO friendly and CSS3 compliant.

Browser Compatibility i.e.; Works for all browsers.

jQuery is  very small, clean code that won’t bog down the loading time of web pages

Highly Documented.There’s a low learning curve. Since it’s based on plain old JavaScript, developers can learn jQuery fast.

Web page elements display even if JavaScript is disabled in the browser.

Simplifies AJAX.

It is extensible – jQuery can be extended to implement customized behavior.

History of jQuery  

      Developed by John Resig.      

      Initial Release –  2006

      Current Version –  3.1.1

      Main site: https://jquery.com/

Basic Structure of jQery

 <script type = “text/javascript”>

  //jQuery detects this state of readiness for you.

    $( document ).ready() method will only run once the page Document Object Model (DOM) is ready for JavaScript code to execute.

              document.write(“Hello, World!”);// to print a string we will use document.write(); method


File Extension of jQuery


Comment Line in jQuery

        Single line comment is done using   //

        Multi-  line comment start with /* and end with */.

Variable Declaration

    In jQuery, you can declare variable in two styles.    

  1. $.name = “value”;

    2.  var variable_name = “value”;