The onclick Event

As we know, the onclick event occurs when an object is clicked. You can find the support for this event in Table 6.61.

Table 6.61. The onclick Event

Event	NS2	NS3	NS4	NS6	IE3a	IE3b	IE4	IE5	IE5.5	IE6
`onclick`	x	x	x	x	x	x	x	x	x	x

Starting in Internet Explorer 4.0, virtually every visible object can have an onclick handler, which was much more than was available in Netscape Navigator 4.0 (which supported onclick for only the <INPUT> , <FORM> , <A> , and <SELECT> elements). Support for onclick is still limited in Netscape Navigator 6.0 compared to Internet Explorerfor example, <H1>-<H6> headers don't have an onclick event in the Netscape Navigator 6.0.

We've worked with the onclick event for a long time already; here's an example from Chapter 1 that displays an alert box when the user clicks a button (it's Listing 01-04.html on the web site):

 <HTML>      <HEAD>          <TITLE>              Executing Scripts in Response to User Action          </TITLE>  <SCRIPT LANGUAGE="JavaScript">   <!--   function alerter()   {   window.alert("You clicked the button!")   }   // -->   </SCRIPT>  </HEAD>      <BODY>          <H1>Executing Scripts in Response to User Action</H1>          <FORM>  <INPUT TYPE="BUTTON" ONCLICK="alerter()" VALUE="Click Me!">  </FORM>      </BODY>  </HTML>

Tip

You can cancel the normal action connected to a click in the Internet Explorer by returning a value of false from the onclick event handler, or by setting window.event.returnValue to false in the event handler.