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More Functions

We can add more functions that get called on different events:

We call a function popup() when the Web page loads
We call a function farewell() when the page is unloaded: the onUnLoad="farewell() attribute is set.

The program also introduces some more objects and some useful applications of JavaScript:

The navigator contains data about the browser being used
The program finds the version of the application appVersion and the userAgent().
This information is displayed in a pop up alert:

Figure: Browser Version JavaScript Example (Netscape and Explorer Shown)
When you leave the Web page or Refresh the page an different alert is brought up:

Figure: Browser Version Page Exit JavaScript Example (Netscape Shown)

The full code for this example is:

<html>
 <head>
   <script language="javascript">

   function popup(){
   var major = parseInt(navigator.appVersion);
   var minor = parseFloat(navigator.appVersion);
   var agent = navigator.userAgent.toLowerCase();

   document.write("<h1>Details in Popup</h1>");
   window.alert(agent + " " + major);
   }

   function farewell(){
   window.alert("Farewell and thanks for visiting");
   }
   </script>
 </head>

<body onLoad="popup()" onUnLoad="farewell()">
</body>
</html>

Dave Marshall
9/28/2001