JavaScript And Java
JavaScript is the scripting language of the Web.JavaScript is used in billions of Web pages to add functionality, validate forms, communicate with the server, and much more
JavaScript's greatest potential gift to a Web site is that scripts can make the page more immediately interactive, that is, interactive without having to submit every little thing to the server for a server program to re-render the page and send it back to the client. For example, consider a top-level navigation panel that has, say, six primary image map links into subsections of the Web site. With only a little bit of scripting, each map area can be instructed to pop up a more detailed list of links to the contents within a subsection whenever the user rolls the cursor atop a map area. With the help of that popup list of links, the user with a scriptable browser can bypass one intermediate menu page. The user without a scriptable browser (or who has disabled JavaScript) will have to drill down through a more traditional and time-consuming path to the desired content.
The JavaScript programming language, developed by Netscape, Inc., is not part of the Java platform.
JavaScript, does not create applets or stand-alone applications. In its most common form today,
JavaScript resides inside HTML documents, and can provide levels of interactivity to web pages that are not achievable with simple HTML.
Java is an OOP programming language while Java Script is an OOP scripting language.
Java creates applications that run in a virtual machine or browser while JavaScript code is run on a browser only.
Java code needs to be compiled while JavaScript code are all in text.
They require different plug
Submit a form using Javascript-JavaScript provides the form object that contains the submit() method. Use the ‘id’ of the form to get the form object.
For example, if the name of your form is ‘myform’, the JavaScript code for the submit call is:
|
document.forms["myform"].submit(); |
But, how to identify a form? Give an id attribute in the form tag
|
<form id='myform' action='formmail.pl'> |
Eg-
<form name="myform" action="handle-data.php">
Search: <input type='text' name='query' />
<a href="javascript: submitform()">Search</a>
</form>
<script type="text/javascript">
function submitform()
{
document.myform.submit();
}
</script>
- How do we get JavaScript onto a web page?
You can use several different methods of placing javascript in you pages.
You can directly add a script element inside the body of page.
1. For example, to add the "last updated line" to your pages, In your page text, add the following:
<p>blah, blah, blah, blah, blah.</p>
<script type="text/javascript" >
<!-- Hiding from old browsers
document.write("Last Updated:" +
document.lastModified);
document.close();
// -->
</script>
<p>yada, yada, yada.</p>
(Note: the first comment, "<--" hides the content of the script from browsers that don't understand javascript. The "// -->" finishes the comment. The "//" tells javascript that this is a comment so javascript doesn't try to interpret the "-->". If your audience has much older browsers, you should put this comments inside your javascript. If most of your audience has newer browsers, the comments can be omitted. For brevity, in most examples here the comments are not shown. )
The above code will look like this on Javascript enabled browsers,
2. Javascript can be placed inside the <head> element
Functions and global variables typically reside inside the <head> element.
<head>
<title>Default Test Page</title>
<script language="JavaScript" type="text/javascript">
var myVar = "";
function timer(){setTimeout('restart()',10);}
document.onload=timer();
</script>
</head>
