呵呵，刚说去干活，突然发现被点名，哈LZ 说的是 Select 自动展开吧，可以实现请参考下贴中俺最后一贴代码【高难？】keyCode的操作。
http://community.csdn.net/Expert/topic/5542/5542762.xml?temp=.8346063干活去了，哈
http://community.csdn.net/Expert/topic/5542/5542762.xml?temp=.8346063干活去了，哈
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<title> new document </title>
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function Dsy()
{
this.Items = {};
this.Provinces = new Array();
this.Cities = new Array();
this.Counties = new Array();
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Dsy.prototype.add = function(id,iArray)
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function change(v)
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var str = "0";
for(i=0;i<v;i++)
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var oSelect = document.getElementById(s[i]);
str += "_"+(oSelect.options[oSelect.selectedIndex].value);
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length = 0;
options[0]=new Option(opt0[v],opt0[v]);
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dsy[strLevelName][i] = ar[i].split(".");
options[length]=new Option(dsy[strLevelName][i][1],i);
} if(v)options[1].selected = true;
}
}
if(++v<s.length){change(v);}
}
}var dsy = new Dsy(); dsy.add("0",["b.北京","a.安徽","f.福建"]); dsy.add("0_0",["b.北京"]);
dsy.add("0_0_0",["b.北京市","d.东城","x.西城","c.崇文","x.宣武","c.朝阳","f.丰台","s.石景山","h.海淀","m.门头沟","f.房山","t.通州","s.顺义","c.昌平","d.大兴","p.平谷","h.怀柔","m.密云","y.延庆"]); dsy.add("0_1",["a.安庆","b.蚌埠","c.巢湖","c.池州","x.滁州","f.阜阳","h.合肥","h.淮北","h.淮南","h.黄山","l.六安","m.马鞍山","s.宿州","t.铜陵","w.芜湖","x.宣城","h.亳州"]);
dsy.add("0_1_0",["a.安庆市","h.怀宁县","q.潜山县","s.宿松县","t.太湖县","t.桐城市","w.望江县","y.岳西县","z.枞阳县"]);
dsy.add("0_1_16",["x.利辛县","m.蒙城县","w.涡阳县","h.亳州市"]); dsy.add("0_2",["f.福州","l.龙岩","n.南平","n.宁德","p.莆田","q.泉州","s.三明","x.厦门","z.漳州"]);
dsy.add("0_2_0",["c.长乐市","f.福清市","f.福州市","l.连江县","l.罗源县","m.闽侯县","m.闽清县","p.平潭县","y.永泰县"]);
dsy.add("0_2_5",["a.安溪县","d.德化县","h.惠安县","j.金门县","j.晋江市","n.南安市","q.泉州市","s.石狮市","y.永春县"]); dsy.add("0_29_8",["苍南县","洞头县","乐清市","平阳县","瑞安市","泰顺县","温州市","文成县","永嘉县"]);
dsy.add("0_29_9",["舟山市","岱山县","嵊泗县"]);
dsy.add("0_30",["重庆"]);
dsy.add("0_30_0",["城口县","大足县"]);
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var s = ["s1","s2","s3"];
var opt0 = ["省份","地级市","市、县级市、县"];
function setup()
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for(i=0;i<s.length;i++)
{
if (i<s.length-1)
{
document.getElementById(s[i]).onchange = new Function("change("+(i+1)+")");
}
document.getElementById(s[i]).onmouseover = function ()
{
this.focus();
};
document.getElementById(s[i]).onkeypress = function ()
{
this.selectedIndex = 0;
var strInitial = String.fromCharCode(event.keyCode).toLowerCase();
this.options.length = 1;
var numIndex = parseInt(this.id.substr(1,1)); var strLevelName;
switch (numIndex)
{
case 1:
strLevelName = "Provinces";
break;
case 2:
strLevelName = "Cities";
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case 3:
strLevelName = "Counties";
break;
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this.selectedIndex = 1;
change(numIndex);
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</head>
<body bgcolor="#E0E0E0" onLoad="setup()">
多级关联菜单：
<form name="frm">
<p>
起点城市
<select id="s1">
<option>省份</option>
</select>
<select id="s2">
<option>地级市</option>
</select>
<select id="s3">
<option>市、县级市、县</option>
</select>
</p>
</form>
</body>
</html>
然后就不必选择每个select时候刷新访问数据库？