Jquery works with a JavaScript Library which is loaded to execute the code. Several standard functions are already written in the linked library so we can directly use them in our code.
How the script works
We must load the Library file first. We can download the file from jquery.com. Or we can use the Content Delivery Network ( CDN) of google , Microsoft or JQuery.com and point to their link. Here is the sample code to link to Google CDN
If you are not using CDN then you can download JQuery files from here. There is one basic file and above that you can download different plugins as per your requirements.
Uncompressed or Minified
Uncompressed files have long variable names, blank space and line breaks etc so it occupies more space. You need this for development of script, modifications etc. For production environment when site is lunched it is better to use minified version as it occupies less space.
Here is a sample code to show a button and show a message associated with on Click event of the button.
<html>
<head>
<title>(Type a title for your page here)</title>
</head>
<body >
<button id=new_one name=button1>My Button</button>
<script src="jquery-3.1.1.min.js"></script>
<script>
$(document).ready(function() {
$('#new_one').click(function(){
alert('Hi , you clicked the button');
})
})
</script>
</body>
</html>
Notice that we have used one external JavaScript file jquery-3.1.1.min.js , this is the main JQuery file which can be linked to get all libraries. You can download JQuery library file from here.
Instead of downloading you can use CDN to link to this file.
We can apply JQuery to different HTML elements. Here is some sample code
Examples:
$(this).hide() - hides the current element. $(this).show() - show the current element. $("p").hide() - hides all <p> elements. $(".my_element").hide() - hides all elements with class="my_element". $("#my_id").hide() - hides the element with id="my_id". $("#my_id").toggle() - toggle element with id="my_id".
Basic syntax of JQUERY
$(document).ready(function(){
// JQuery code written here ...
});
We will display an alert window from a button click. For showing alert window there is no need to use JQuery but with this we will learn how click event is triggered.
The element which can fire the click event can be identified by its assigned class, like this
Here is a problem. Once the same class is assigned to different elements then all those elements will fire the click event. Check this code. Here on Click of input text box also will display the alert window.
To differentiate each element of a webpage we will assign unique id to the element.
This is a div layer ( Hide Me )
<script>
$(document).ready(function(){
$("#button1").click(function(){
$("#basic_div").toggle();
});
});
</script>
<input type=button value='Hide / Un-Hide Layer' id="button1">
<div id="basic_div" style="width: 100px; height: 100px; background: yellow;padding-left:12px;"> This is a div layer ( Hide Me )</div>
Opening closing and passing data between parent & child window
Frequently Used Code
$('#empno').focus(); // focus on text box with id empno
$('#empno').select(); // select all text inside text box with id empno
$('#empno').focus().select(); // better way with less code
Form reset (id=data)
$('form#data').trigger("reset");
$("#t1").css("background-color", "yellow"); // Set Background color to yellow
JQuery Video Tutorials