位置
theObject = document.getElementById("autocompletediv");
//设置为可见
theObject.style.visibility = "visible";
theObject.style.width = "152px";
//设置检索标签位置
var posx = 0;
var posy = 0;
posx = (findPosX (document.getElementById("yourname")) + 1);
posy = (findPosY (document.getElementById("yourname")) + 23);
theObject.style.left = posx + "px";
theObject.style.top = posy + "px";
//设定事件为键盘录入
var theextrachar = e.which;
if (theextrachar == undefined){
theextrachar = e.keyCode;
}
//设定加载检索名单位置
var objID = "autocompletediv";
//设定PHP请求页面，并将用户输入的姓名传值过去（同时考虑到Backspace作用）
if (theextrachar == 8){
if (thevalue.length == 1){
var serverPage = "autocomp.php";
}
else{
var serverPage = "autocomp.php" + "?sstring=" + thevalue.substr(0, (thevalue.length -1));
}
}
else{
var serverPage = "autocomp.php" + "?sstring=" + thevalue + String.fromCharCode(theextrachar);
}
//发送请求并加载返回数据
var obj = document.getElementById(objID);
xmlhttp.open("GET", serverPage);
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
obj.innerHTML = xmlhttp.responseText;
}
}
xmlhttp.send(null);
}

来源：php中文网