JavaScript Events

Details
Category: Contact Enhanced
JavaScript Events are items that transpire based on an action. A document event is the loading of an HTML document. A form event is the clicking on a button. Events are objects with properties.

Event Properties

JavaScript defines five types of events which are form, image, image map, link, and window events. Events are associated with HTML tags. The definitions of the events described below are as follows:

Form Events

Image Events

Image Map Events

Link Events

Window Events

Event Association

Events are associated with HTML tags. The definitions of the events described below are as follows:

The events for each HTML tag are as follows:

Event Handlers

Event handlers are created as follows:

onEvent = "Code to handle the event"

The following example demonstrates its use:

<a href="/independent/index.html" target="_top" onMouseOver="window.status='To Independent Technologies Section' ;return true" onMouseOut="window.status='';return true"><img SRC="gifs/greenindependentbutton2.gif" ALT="Independent Technologies" VSPACE=3 BORDER=0 height=35 width=120></a><BR>

As you can see, the event handling attribute is included in the HTML tag. When multiple statements are included in the event handling code, the statements are separated by a semicolon.

The following example can be used to redirect a link to another location:

<HTML>
<HEAD>
<TITLE>Using functions as event handlers</TITLE>
<SCRIPT LANGUAGE="JavaScript">
<!--
function nameDefined(ckie,nme)
{
   var splitValues
   var i
   for (i=0;i<ckie.length;++i)
   {
      splitValues=ckie[i].split("=")
      if (splitValues[0]==nme) return true
   }
   return false
}
function delBlanks(strng)
{
   var result=""
   var i
   var chrn
   for (i=0;i<strng.length;++i) {
      chrn=strng.charAt(i)
      if (chrn!=" ") result += chrn
   }
   return result
}
function getCookieValue(ckie,nme)
{
   var splitValues
   var i
   for(i=0;i<ckie.length;++i) {
      splitValues=ckie[i].split("=")
      if(splitValues[0]==nme) return splitValues[1]
   }
   return ""
}
function testCookie(cname, cvalue) {  //Tests to see if the cookie 
   var cookie=document.cookie        //with the name and value 
   var chkdCookie=delBlanks(cookie)  //are on the client computer
   var nvpair=chkdCookie.split(";")
   if(nameDefined(nvpair,cname))  //See if the name is in any pair
   {   
      tvalue=getCookieValue(nvpair,cname)  //Gets the value of the cookie
      if (tvalue == cvalue) return true
	   else return false
   }
   else return false
}
function redirectLink() {
   if (testCookie("javahere", "yes")) {
      window.location="javahere.html"
   }
   else{
      var futdate = new Date()
      var expdate = futdate.getTime()
      expdate += 3600*1000  //expires in 1 hour(milliseconds)
      futdate.setTime(expdate)
      var newCookie="javahere=yes; path=/;"
      newCookie += " expires=" + futdate.toGMTString()
      window.document.cookie=newCookie
      window.location="javanot.html"
   }
}
//-->
</SCRIPT>
</HEAD>
<BODY>
<H3>Using an event handler to direct a link based on a cookie value</H3>
<P>
<A NAME="Here" onClick="return redirectLink()">See if you've been here.</A>
</P>
</BODY>
</HTML>