1. What is $ in jQuery?
The $ represents the jQuery Function, and is actually a shorthand alias for jQuery. Prototype, jQuery, and most javascript libraries use the $ as the primary base object (or function). Most of them also have a way to relinquish the $ so that it can be used with another library that uses it. In that case you use “jQuery” instead of “$”. In fact, “$” is just a shortcut for “jQuery”. JavaScript allows upper and lower letters, numbers, and $ and _. The $ was intended to be used for machine-generated variables (such as $0001).
2. How to use?
You can load the jquery class from Google AJAX Libraries API.
<script type="text/javascript" src="http://www.google.com/jsapi"></script>
<script>
google.load("jquery", "1.4.0");
</script>
or
You can also download the jQuery libraries files from the jQuery site http://hinturl.com/jquerydownload to your application folder and include directly to the code.
<script type="text/javascript" src="jQuery.js"></script>
3. Write your first jQuery program?
<html>
<head>
<script src="jquery/jquery.js" type="text/javascript"></script>
</head>
<body>
<script type="text/javascript">
$(document).ready(function(){
alert("Hello World From JQuery!!");
});
</script>
</body>
</html>
Here the $(document) is the jQuery function which passes the document as the “selector“. And the .ready() is the event for document object. Refer http://hinturl.com/jquery-doument-events for other events.
And the above code you can write in this way also.
<script type="text/javascript">
jQuery(document).ready(function(){
alert("Hello World From JQuery!!");
});
</script>
$() is replaced with jQuery().
