Cara Membuat Combo-box Viewer

Langkah Pertama:

<style type='text/css'>
.dropcontent{
width: 300px;
height: 140px;
border: 1px solid black;
background-color: #FFECC6;
display:block;
}
</style>

<script type='text/javascript'>
//<![CDATA[
/*
Combo-Box Viewer script- Created by and © Dynamicdrive.com
Visit http://www.dynamicdrive.com/ for this script and more
This notice MUST stay intact for legal use
*/

if (document.getElementById){
document.write('<style type="text/css">\n')
document.write('.dropcontent{display:none;}\n')
document.write('</style>\n')
}

function contractall(){
if (document.getElementById){
var inc=0
while (document.getElementById("dropmsg"+inc)){
document.getElementById("dropmsg"+inc).style.display="none"
inc++
}
}
}

function expandone(){
if (document.getElementById){
var selectedItem=document.dropmsgform.dropmsgoption.selectedIndex
contractall()
document.getElementById("dropmsg"+selectedItem).style.display="block"
}
}

if (window.addEventListener)
window.addEventListener("load", expandone, false)
else if (window.attachEvent)
window.attachEvent("onload", expandone)

//]]></script>

<form name="dropmsgform">
<select name="dropmsgoption" size="1" style="width:300" onChange="expandone()">
<option selected>What is JavaScript?</option>
<option>Difference betwen Java and JavaScript</option>
<option>What is DHTML?</option>
</select>

<div id="dropmsg0" class="dropcontent">
JavaScript is a scripting language originally developed by Netscape to add interactivity and power to web documents. It is purely client side, and runs completely on the client's browser and computer.
</div>

<div id="dropmsg1" class="dropcontent">
Java is completely different from JavaScript- it's more powerful, more complex, and unfortunately, a lot harder to master. It belongs in the same league as C, C++, and other more complex languages. Java programs need to be compiled before they can run, while JavaScript do not.
</div>

<div id="dropmsg2" class="dropcontent">
DHTML is the embodiment of a combination of technologies- JavaScript, CSS, and HTML. Through them a new level of interactivity is possible for the end user experience.
</div>
</form>