Slide 11.b: JavaScript (cont.)

JavaScript (Cont.)

What Can a JavaScript Do?

JavaScript gives HTML designers a programming tool—HTML authors are normally not programmers, but JavaScript is a scripting language with a very simple syntax! Almost anyone can put small “snippets” of code into their HTML pages.

JavaScript can put dynamic text into an HTML page—A JavaScript statement like this: document.write("<h1>" + name + "</h1>") can write a variable text into an HTML page

JavaScript can react to events—A JavaScript can be set to execute when something happens, like when a page has finished loading or when a user clicks on an HTML element.

JavaScript can read and write HTML elements—A JavaScript can read and change the content of an HTML element.

JavaScript can be used to validate data—A JavaScript can be used to validate form data before it is submitted to a server. This saves the server from extra processing.

JavaScript can be used to detect the visitor's browser—A JavaScript can be used to detect the visitor's browser, and—depending on the browser—load another page specifically designed for that browser.

JavaScript can be used to create cookies—A JavaScript can be used to store and retrieve information on the visitor's computer.

How to Put a JavaScript into an HTML Page

The HTML <script> tag is used to insert a JavaScript into an HTML page. The code will produce this output on an HTML page: “Hello, World!”

 <html><body>
  <script type="text/javascript">
   document.write( "Hello, World!" )
  </script>
 </body></html>

Demonstration


<html> <head> <script type="text/javascript"> </script> </head> <body> <script type="text/javascript"> </script> </body> </html>