下拉菜单输入,根据输入内容自动定位

　　下拉菜单支持输入，并根据输入内容自动定位：

参考：演员发表于 10/23/2001 8:58:16 AM 的文章 “罗亭的可输入下拉框的解密简化版.”，在此特别感谢相关人等。

本文为这个下拉框增加了一点小小的功能：输入能够定位在已有的选择框内。还有一个缺点，各位给改改：输入的时候不能够自动拉开选择框，怎么办？

function getLeftPostion( theObj )
{
var pos = 0;
while ( theObj != null )
{
pos += theObj.offsetLeft;
//get the Object which contain theObj.
theObj = theObj.offsetParent;
}
return pos;
}
function getTopPostion( theObj )
{
var pos = 0;
while ( theObj != null )
{
pos += theObj.offsetTop;
//get the Object which contain theObj.
theObj = theObj.offsetParent;
}
return pos;
}
function checkVersion()
{
var isBadVersion=true;
var curVer=navigator.appVersion;
if (pos>=1)
{
var intVer=parseInt(curVer.charAt(pos+5));
if (intVer>=5)
{ isBadVersion=false;}
}
if (isBadVersion)
{
var msg=This page may not be displayed properly: +
This product requires Microsoft Internet Explorer 5 or later browser only.;
alert(msg);
}
}

//check the browser version
checkVersion();

// the array of comboBoies
theArray = new Array();

function combobox(objId, objHandler)
{
this.getValue = getValue;
this.doResize = doResize;
this.doChange = doChange;
this.loseFocus = loseFocus;
this.doSelectIdx = doSelectIdx;
this.focus = focus;
this.keyPress = keyPress;
this.change = change;

var strMsg=;

//------------------------------------------------------------------------------------------------------
// create the text object
//------------------------------------------------------------------------------------------------------
var txtObjIdName = objId + _text;

if (document.all[txtObjIdName] != null)
{
strMsg=The following id: + txtObjIdName + is used internally by the Combo Box! +
Use of this id in your page may cause malfunction. Please use another id for your controls.;
alert(strMsg);
}

var txtInner = <INPUT type=text id= + txtObjIdName + name= + txtObjIdName + onblur= + objHandler + .loseFocus() + onkeyup= + objHandler + .keyPress() + onchange= + objHandler + .keyPress() + style=display: none; position: absolute value= >;