现在很多网站都有这种效果，在文本框输入一个字符，下边会出来相匹配的内容，这个代码就演示了这个功能是如何完成的，当然，这是个静态的，你可以将提示的内容从数据库读取出来，要用到AJAX那东东。
<HTML>
<HEAD>
<title>带输入匹配的文本框</title>
<style>
body,div {
font-family:verdana;
line-height:100%;
font-size:10pt;
}
input {
width:320px;
}
h1 {
text-align:center;
font-size:2.2em;
}
#divc {
border:1px solid #555;
}
.des {
width:500px;
background-color:lightyellow;
border:1px solid #555;
padding:25px;
margin-top:25px;
}
.mouseover {
color:#ffffff;
background-color:highlight;
width:100%;
cursor:default;
}
.mouseout {
color:#000;
width:100%;
background-color:#ffffff;
cursor:default;
}
</style>
<SCRIPT LANGUAGE="JavaScript">
<!--
function jsAuto(instanceName,objID)
{
this._msg = [];
this._x = null;
this._o = document.getElementById( objID );
if (!this._o) return;
this._f = null;
this._i = instanceName;
this._r = null;
this._c = 0;
this._s = false;
this._v = null;
this._o.style.visibility = "hidden";
this._o.style.position = "absolute";
this._o.style.zIndex = "9999";
this._o.style.overflow = "auto";
this._o.style.height = "50";
return this;
};
jsAuto.prototype.directionKey=function() { with (this)
{
var e = _e.keyCode ? _e.keyCode : _e.which;
var l = _o.childNodes.length;
(_c>l-1 || _c<0) ? _s=false : "";
if( e==40 && _s )
{
_o.childNodes[_c].className="mouseout";
(_c >= l-1) ? _c=0 : _c ++;
_o.childNodes[_c].className="mouseover";
}
if( e==38 && _s )
{
_o.childNodes[_c].className="mouseout";
_c--<=0 ? _c = _o.childNodes.length-1 : "";
_o.childNodes[_c].className="mouseover";
}
if( e==13 )
{
if(_o.childNodes[_c] && _o.style.visibility=="visible")
{
_r.value = _x[_c];
_o.style.visibility = "hidden";
}
}
if( !_s )
{
_c = 0;
_o.childNodes[_c].className="mouseover";
_s = true;
}
}};
// mouseEvent.
jsAuto.prototype.domouseover=function(obj) { with (this)
{
_o.childNodes[_c].className = "mouseout";
_c = 0;
obj.tagName=="DIV" ? obj.className="mouseover" : obj.parentElement.className="mouseover";
}};
jsAuto.prototype.domouseout=function(obj)
{
obj.tagName=="DIV" ? obj.className="mouseout" : obj.parentElement.className="mouseout";
};
jsAuto.prototype.doclick=function(msg) { with (this)
{
if(_r)
{
_r.value = msg;
_o.style.visibility = "hidden";
}
else
{
alert("javascript autocomplete ERROR :\n\n can not get return object.");
return;
}
}};
// object method;
jsAuto.prototype.item=function(msg)
{
if( msg.indexOf(",")>0 )
{
var arrMsg=msg.split(",");
for(var i=0; i<arrMsg.length; i++)
{
arrMsg[i] ? this._msg.push(arrMsg[i]) : "";
}
}
else
{
this._msg.push(msg);
}
this._msg.sort();
};
jsAuto.prototype.append=function(msg) { with (this)
{
_i ? "" : _i = eval(_i);
_x.push(msg);
var div = document.createElement("DIV");
//bind event to object.
div.onmouseover = function(){_i.domouseover(this)};
div.onmouseout = function(){_i.domouseout(this)};
div.onclick = function(){_i.doclick(msg)};
var re = new RegExp("(" + _v + ")","i");
div.style.lineHeight="140%";
div.className = "mouseout";
if (_v) div.innerHTML = msg.replace(re , "<strong>$1</strong>");
div.style.fontFamily = "verdana";
_o.appendChild(div);
}};
jsAuto.prototype.display=function() { with(this)
{
if(_f && _v!="")
{
_o.style.left = _r.offsetLeft;
_o.style.width = _r.offsetWidth;
_o.style.top = _r.offsetTop + _r.offsetHeight;
_o.style.visibility = "visible";
}
else
{
_o.style.visibility="hidden";
}
}};
jsAuto.prototype.handleEvent=function(fValue,fID,event) { with (this)
{
var re;
_e = event;
var e = _e.keyCode ? _e.keyCode : _e.which;
_x = [];
_f = false;
_r = document.getElementById( fID );
_v = fValue;
_i = eval(_i);
re = new RegExp("^" + fValue + "", "i");
_o.innerHTML="";
for(var i=0; i<_msg.length; i++)
{
if(re.test(_msg[i]))
{
_i.append(_msg[i]);
_f = true;
}
}
_i ? _i.display() : alert("can not get instance");
if(_f)
{
if((e==38 || e==40 || e==13))
{
_i.directionKey();
}
else
{
_c=0;
_o.childNodes[_c].className = "mouseover";
_s=true;
}
}
}};
window.onerror=new Function("return true;");
//-->
</SCRIPT>
</HEAD>
<BODY>
<div id="divc">
<!--this is the autocomplete container.-->
</div>
<div align="center">
<input onkeyup="jsAutoInstance.handleEvent(this.value,'auto',event)" id="auto">
</div>
<SCRIPT LANGUAGE="JavaScript">
<!--
var jsAutoInstance = new jsAuto("jsAutoInstance","divc");
jsAutoInstance.item("a-start,b-start,c-start,d-start,e-start,f-start,g-start,h-start,i-start,j-start,k-start,l-start,m-start,n-start,o-start,p-start,q-start,r-start,s-start,t-start,u-start,v-start,w-start,x-start,y-start,z-start,z-start,a-start,b-start,c-start,d-start,e-start,f-start,g-start,h-start,i-start,j-start,k-start,l-start,m-start,n-start,o-start,p-start,q-start,r-start,s-start,t-start,u-start,v-start,w-start,x-start,y-start,z-start,u-start,v-start,w-start,x-start,y-start,z-start,z-start,a-start,b-start,c-start,y-start,z-start,z-start,a-start,b-start,c-start,d-start,e-start,f-start,g-start,h-start,i-start,s-start,w-start,x-start,y-start,z-start,z-start,a-start,b-start,c-start,d-start,e-start,f-start,g-start,h-start,i-start,a-start,b-start,c-start,d-start,e-start,z-start,z-start");
jsAutoInstance.item("blueDestiny");
jsAutoInstance.item("BlueMiracle,Blue");
jsAutoInstance.item("angela,geniuslau");
jsAutoInstance.item("never-online");
//-->
</SCRIPT>
<center>请在输入框输入一个字母：</center>
</BODY>
</HTML>