</form>
<SCRIPT LANGUAGE="JavaScript">
<!--
var selecttext=""
+"搜索@search|Google@http://www.google.com/^Yahoo@http://www.yahoo.com/"
+"*收藏@fav|无忧视窗@http://www.51windows.Net/^蓝色理想@http://www.blueidea.com/^POPO@http://plod.popoever.net/"
+"";
var test1 = new HwTwoSelect(document.myform.a,document.myform.b,selecttext,"－分类－@","－网址－@",1);//最后的参数表示，选了一级菜单后，二级菜单是否还要显示“请选择”，1或true代码，不显示，0或false代表显示
TwoSelectInit(test1);

var test2 = new HwTwoSelect(document.myform.aa,document.myform.bb,selecttext,"－分类－@","－网址－@",0);
TwoSelectInit(test2);

var test3 = new HwTwoSelect(document.myform.aaa,document.myform.bbb,selecttext,"－分类－@","－网址－@",0);
TwoSelectInit(test3,"fav","http://www.51windows.Net/");
//-->
</SCRIPT>

以下是示例代码，详细请查看源文件：

<form method="post" name=myform>
<select name="select1" onchange="TwoSelectInit(ttt,this.value)"></select>　<select name="select2"></select><hr>
</form>

<SCRIPT LANGUAGE="JavaScript">
<!--
var selecttext=""
+"搜索@search|Google@http://www.google.com/^Yahoo@http://www.yahoo.com/"
+"*收藏@fav|无忧视窗@http://www.51windows.Net/^蓝色理想@http://www.blueidea.com/^POPO@http://plod.popoever.net/"
+"";

var ttt = new HwTwoSelect(document.myform.select1,document.myform.select2,selecttext,"－分类－@","－网址－@",1);
TwoSelectInit(ttt ,"fav","http://www.51windows.Net/");

//-->
</SCRIPT>

bug:在二级菜单有初始值时，如果表单重置，二级菜单的值会变为空

 var _SNameArr = _SName.split("|")
 var _SName1,_SName2,_SName3
 var _SName1 = _SNameArr[0]
 var _SName2 = (_SNameArr.length>1)?_SNameArr[1]:_SNameArr[0]
 var _SName3 = (_SNameArr.length>2)?_SNameArr[2]:_SNameArr[0]

 var _SValueArr = _SValue.split("|")
 var _SValue1,_SValue2,_SValue3
 var _SValue1 = _SValueArr[0]
 var _SValue2 = (_SValueArr.length>1)?_SValueArr[1]:_SValueArr[0]
 var _SValue3 = (_SValueArr.length>2)?_SValueArr[2]:_SValueArr[0]

 if (ShowType==3){
  _AllOptionStr = _AllOptionStr.replace(/\(\(/ig,"\(\("+_Ds3+"\^")
  _AllOptionStr = _AllOptionStr.replace(/\{\{/ig,"\{\{"+_Ds2+"\(\("+_Ds3+"\*\*")
 }
 else if(ShowType==2){
  _AllOptionStr = _AllOptionStr.replace(/\{\{/ig,"\{\{"+_Ds2+"\(\("+_Ds3+"\*\*")
 }
 else if(ShowType==1){
  _AllOptionStr = _AllOptionStr.replace(/\(\(/ig,"\(\("+_Ds3+"\^")
 }
 var AllStr = _Ds1 + "{{"+ _Ds2 + "(("+ _Ds3 +"||"+_AllOptionStr
 //alert(AllStr)
 var _AR0 = AllStr.split("||");
 document.writeln("<select name=\"" + _SName1 + "\" size=\"1\" onChange=\""+_SName1+"redirect(this.options.selectedIndex)\">");
 for (var i1 = 0;i1 < _AR0.length;i1++)
 {
  var Area1Str = _AR0[i1];
  var _AR10 = Area1Str.split("{{");
  var _AR11 = _AR10[0].split("@");
  var Tstr1 = _AR11[0];
  var Vstr1 = (_AR11.length==2)?_AR11[1]:_AR11[0]
  document.writeln("<option value=\""+Vstr1+"\">"+Tstr1+"<\/option>");
 }
 document.writeln("<\/select>");

 document.writeln("<select name=\"" + _SName2 + "\" size=\"1\" onChange=\""+_SName1+"redirect1(this.options.selectedIndex)\">");
 var _AR111 = _Ds2.split("@");
 var Tstr11 = _AR111[0];
 var Vstr11 = (_AR111.length==2)?_AR111[1]:_AR111[0];
 document.writeln("<option value=\""+Vstr11+"\">"+Tstr11+"<\/option>");
 document.writeln("<\/select>");

 document.writeln("<select name=\"" + _SName3 + "\" size=\"1\">");
 var _AR222 = _Ds3.split("@");
 var Tstr22 = _AR222[0];
 var Vstr22 = (_AR222.length==2)?_AR222[1]:_AR222[0];
 document.writeln("<option value=\""+Vstr22+"\">"+Tstr22+"<\/option>");
 document.writeln("<\/select>");

 document.writeln("<S"+"CRIPT LANGUAGE=\"JavaScript\" defer>");
 document.writeln("<!--");
 document.writeln("var "+_SName1+"NewAllStr = \""+ AllStr +"\"");
 document.writeln("var "+_SName1+"_AR0 = "+_SName1+"NewAllStr.split(\"||\");");
 document.writeln("var "+_SName1+"groups=document."+ _FormName +"." + _SName1 + ".options.length;");
 document.writeln("var "+_SName1+"group=new Array("+_SName1+"groups)");
 document.writeln("for (i=0; i<"+_SName1+"groups; i++){");
 document.writeln(" "+_SName1+"group[i]=new Array();");
 document.writeln("}");
 document.writeln("for (var i1 = 0;i1 < "+_SName1+"_AR0.length;i1++){");
 document.writeln(" var Area1Str = "+_SName1+"_AR0[i1];");
 document.writeln(" var _AR10 = Area1Str.split(\"{{\");");
 document.writeln(" var _AR12 = _AR10[1].split(\"**\");");
 document.writeln(" for (var i2 = 0;i2 < _AR12.length;i2++){");
 document.writeln("  var Area2Str = _AR12[i2];");
 document.writeln("  var _AR20 = Area2Str.split(\"((\");");
 document.writeln("  var _AR211 = _AR20[0].split(\"@\");");
 document.writeln("  var Tstr2 = _AR211[0];");
 document.writeln("  var Vstr2 = (_AR211.length==2)?_AR211[1]:_AR211[0];");
 document.writeln("  "+_SName1+"group[i1][i2]=new Option(Tstr2,Vstr2);");
 document.writeln(" }");
 document.writeln("}");
 document.writeln("var "+_SName1+"temp = document."+ _FormName +"." + _SName2);
 document.writeln("function "+_SName1+"redirect(x){");
 document.writeln(" for (m="+_SName1+"temp.options.length-1;m>0;m--)");
 document.writeln(" "+_SName1+"temp.options[m]=null;");
 document.writeln(" for (i=0;i<"+_SName1+"group[x].length;i++){");
 document.writeln("  "+_SName1+"temp.options[i]=new Option("+_SName1+"group[x][i].text,"+_SName1+"group[x][i].value);");
 document.writeln(" }");
 document.writeln(" "+_SName1+"temp.options[0].selected=true");
 document.writeln(" "+_SName1+"redirect1(0)");
 document.writeln("}");
 document.writeln("var "+_SName1+"Group2s=document."+ _FormName +"." + _SName2 + ".options.length;");
 document.writeln("var "+_SName1+"Group2=new Array("+_SName1+"groups);");
 document.writeln("for (i=0; i<"+_SName1+"groups; i++){");
 document.writeln(" "+_SName1+"Group2[i]=new Array("+_SName1+"group[i].length)");
 document.writeln(" for (j=0; j<"+_SName1+"group[i].length; j++){");
 document.writeln("  "+_SName1+"Group2[i][j]=new Array()");
 document.writeln(" }");
 document.writeln("}");
 document.writeln("for (var i1 = 0;i1 < "+_SName1+"_AR0.length;i1++){");
 document.writeln(" var Area1Str = "+_SName1+"_AR0[i1]");
 document.writeln(" var _AR10 = Area1Str.split(\"{{\");");
 document.writeln(" var _AR12 = _AR10[1].split(\"**\");");
 document.writeln(" for (var i2 = 0;i2 < _AR12.length;i2++){");
 document.writeln("  var Area2Str = _AR12[i2]");
 document.writeln("  var _AR20 = Area2Str.split(\"((\");");
 document.writeln("  _AR212 = _AR20[1].split(\"^\");");
 document.writeln("  for (var i3 = 0;i3 < _AR212.length;i3++){");
 document.writeln("   Area3Str = _AR212[i3]");
 document.writeln("   _AR3 = Area3Str.split(\"@\");");
 document.writeln("   Tstr3 = _AR3[0]");
 document.writeln("   Vstr3 = (_AR3.length==2)?_AR3[1]:_AR3[0]");
 document.writeln("   "+_SName1+"Group2[i1][i2][i3]=new Option(Tstr3,Vstr3);");
 document.writeln("  }");
 document.writeln(" }");
 document.writeln("}");
 document.writeln("var "+_SName1+"temp1=document."+ _FormName +"." + _SName3 + "");
 document.writeln("function "+_SName1+"redirect1(y){");
 document.writeln(" for (m="+_SName1+"temp1.options.length-1;m>0;m--)");
 document.writeln(" "+_SName1+"temp1.options[m]=null");
 document.writeln(" for (i=0;i<"+_SName1+"Group2[document."+ _FormName +"." + _SName1 + ".options.selectedIndex][y].length;i++){");
 document.writeln("  "+_SName1+"temp1.options[i]=new Option("+_SName1+"Group2[document."+ _FormName +"." + _SName1 + ".options.selectedIndex][y][i].text," + _SName1 + "Group2[document."+ _FormName +"." + _SName1 + ".options.selectedIndex][y][i].value)");
 document.writeln(" }");
 document.writeln(" "+_SName1+"temp1.options[0].selected=true");
 document.writeln("}");
 document.writeln("\/\/-->");
 document.writeln("<\/script>");
 document.writeln("<s"+"cript language=\"JavaScript\">");
 document.writeln("<!--");
 document.writeln("function "+_SName1+"SetValue(){");
 document.writeln(" try{");
 document.writeln("  if (\""+_SValue1+"\"!=\"\"){");
 document.writeln("   document."+ _FormName +"."+_SName1+".value=\""+_SValue1+"\"");
 document.writeln("   "+_SName1+"redirect(document."+ _FormName +"."+_SName1+".options.selectedIndex);");
 document.writeln("   if (\""+_SValue2+"\"!=\"\"){");
 document.writeln("    document."+ _FormName +"."+_SName2+".value=\""+_SValue2+"\"");
 document.writeln("    "+_SName1+"redirect1(document."+ _FormName +"."+_SName2+".options.selectedIndex)");
 document.writeln("    if (\""+_SValue3+"\"!=\"\")");
 document.writeln("     document."+ _FormName +"."+_SName3+".value=\""+_SValue3+"\"");
 document.writeln("   }");
 document.writeln("  }");
 document.writeln(" }");
 document.writeln(" catch(e){");
 document.writeln(" }");
 document.writeln("}");
 document.writeln("window.attachEvent(\"onload\","+_SName1+"SetValue)");
 document.writeln("\/\/-->");
 document.writeln("<\/script>");
}
//-->
</script>

<SCRIPT LANGUAGE="JavaScript">
<!--
var AllStr1 = ""
+"东北地区{{"
 +"黑龙江((哈尔滨^齐齐哈尔^牡丹江^佳木斯^大庆^绥化^鹤岗^鸡西^黑河^双鸭山^伊春^七台河^大兴安岭"
 +"**吉林((长春^吉林^四平^辽源^通化^白山^松原^白城^延边"
 +"**辽宁((沈阳^大连^鞍山^抚顺^本溪^丹东^锦州^营口^阜新^辽阳^盘锦^铁岭^朝阳^葫芦岛"
+"||华北地区{{"
 +"北京((东城^西城^崇文^宣武^朝阳^丰台^石景山^海淀^门头沟^房山^通州^顺义^昌平^大兴^平谷^怀柔^密云^延庆"
 +"**天津((和平^东丽^河东^西青^河西^津南^南开^北辰^河北^武清^红挢^塘沽^汉沽^大港^宁河^静海^宝坻^蓟县"
 +"**山东((济南^青岛^淄博^枣庄^东营^烟台^潍坊^济宁^泰安^威海^日照^莱芜^临沂^德州^聊城^滨州^菏泽"
 +"**河北((石家庄^邯郸^邢台^保定^张家口^承德^廊坊^唐山^秦皇岛^沧州^衡水"
 +"**河南((郑州^开封^洛阳^平顶山^安阳^鹤壁^新乡^焦作^濮阳^许昌^漯河^三门峡^南阳^商丘^信阳^周口^驻马店^济源"
 +"**山西((太原^大同^阳泉^长治^晋城^朔州^吕梁^忻州^晋中^临汾^运城"
 +"**内蒙古((呼和浩特^包头^乌海^赤峰^呼伦贝尔盟^阿拉善盟^哲里木盟^兴安盟^乌兰察布盟^锡林郭勒盟^巴彦淖尔盟^伊克昭盟"
+"||华中地区{{"
 +"湖北((武汉^宜昌^荆州^襄樊^黄石^荆门^黄冈^十堰^恩施^潜江^天门^仙桃^随州^咸宁^孝感^鄂州"
 +"**湖南((长沙^常德^株洲^湘潭^衡阳^岳阳^邵阳^益阳^娄底^怀化^郴州^永州^湘西^张家界"
+"||华南地区{{"
 +"广东((广州^深圳^珠海^汕头^东莞^中山^佛山^韶关^江门^湛江^茂名^肇庆^惠州^梅州^汕尾^河源^阳江^清远^潮州^揭阳^云浮"
 +"**广西((南宁^柳州^桂林^梧州^北海^防城港^钦州^贵港^玉林^南宁地区^柳州地区^贺州^百色^河池"
 +"**福建((福州^厦门^莆田^三明^泉州^漳州^南平^龙岩^宁德"
 +"**海南((海口^三亚"
+"||西南地区{{"
 +"四川((成都^绵阳^德阳^自贡^攀枝花^广元^内江^乐山^南充^宜宾^广安^达川^雅安^眉山^甘孜^凉山^泸州"
 +"**重庆((万州^涪陵^渝中^大渡口^江北^沙坪坝^九龙坡^南岸^北碚^万盛^双挢^渝北^巴南^黔江^长寿^綦江^潼南^铜梁^大足^荣昌^壁山^梁平^城口^丰都^垫江^武隆^忠县^开县^云阳^奉节^巫山^巫溪^石柱^秀山^酉阳^彭水^江津^合川^永川^南川"
 +"**贵州((贵阳^六盘水^遵义^安顺^铜仁^黔西南^毕节^黔东南^黔南"
 +"**云南((昆明^大理^曲靖^玉溪^昭通^楚雄^红河^文山^思茅^西双版纳^保山^德宏^丽江^怒江^迪庆^临沧"
 +"**西藏((拉萨^日喀则^山南^林芝^昌都^阿里^那曲"
+"||西北地区{{"
 +"陕西((西安^宝鸡^咸阳^铜川^渭南^延安^榆林^汉中^安康^商洛"
 +"**甘肃((兰州^嘉峪关^金昌^白银^天水^酒泉^张掖^武威^定西^陇南^平凉^庆阳^临夏^甘南"
 +"**宁夏((银川^石嘴山^吴忠^固原"
 +"**青海((西宁^海东^海南^海北^黄南^玉树^果洛^海西"
 +"**新疆((乌鲁木齐^石河子^克拉玛依^伊犁^巴音郭勒^昌吉^克孜勒苏柯尔克孜^博尔塔拉^吐鲁番^哈密^喀什^和田^阿克苏"
+"||华东地区{{"
 +"上海((黄浦^卢湾^徐汇^长宁^静安^普陀^闸北^虹口^杨浦^闵行^宝山^嘉定^浦东^金山^松江^青浦^南汇^奉贤^崇明"
 +"**江苏((南京^镇江^苏州^南通^扬州^盐城^徐州^连云港^常州^无锡^宿迁^泰州^淮安"
 +"**浙江((杭州^宁波^温州^嘉兴^湖州^绍兴^金华^衢州^舟山^台州^丽水"
 +"**安徽((合肥^芜湖^蚌埠^马鞍山^淮北^铜陵^安庆^黄山^滁州^宿州^池州^淮南^巢湖^阜阳^六安^宣城^亳州"
 +"**江西((南昌市^景德镇^九江^鹰潭^萍乡^新馀^赣州^吉安^宜春^抚州^上饶"
+"||港澳台地区{{"
 +"香港((香港"
 +"**澳门((澳门"
 +"**台湾((台北^高雄^台中^台南^屏东^南投^云林^新竹^彰化^苗栗^嘉义^花莲^桃园^宜兰^基隆^台东^金门^马祖^澎湖"
+"||其它地区{{"
 +"其它((其它"
//-->
</SCRIPT>

以下代码加到body中（简要说明之前）
<FORM name="HwForm">
<HR>选择一次<br>
<SCRIPT LANGUAGE="JavaScript">
CreateSelect("","S_13|S_23|S_33","","请选择地区@|请选择省份@|请选择城市@",AllStr1,0);
</SCRIPT>

<HR>选择三次<br>
<SCRIPT LANGUAGE="JavaScript">
CreateSelect("HwForm","S_1|S_2|S_3","华北地区|山东|济宁","请选择地区@|请选择省份@|请选择城市@",AllStr1,3);
</SCRIPT>

<SCRIPT LANGUAGE="JavaScript">
<!--
var AllStr2 = ""
+"笔记本{{"
 +"IBM((R32^T40^T42"
 +"**DELL((N600^M600"
+"||数码相机{{"
 +"CANON((A75^A80^A85"
 +"**SONY((S80^S60"
//-->
</SCRIPT>

<HR>选择二次<br><SCRIPT LANGUAGE="JavaScript">
CreateSelect("HwForm","S_11|S_21|S_31","笔记本|IBM|T42","请选择分类@|请选择品牌@|请选择系列@",AllStr2,2);
</SCRIPT>

<HR>选择二次<br><SCRIPT LANGUAGE="JavaScript">
CreateSelect("HwForm","S_12|S_22|S_32","","请选择分类@|请选择品牌@|请选择系列@",AllStr2,1);
</SCRIPT>
</FORM>

简要说明：

<FORM name="HwForm">
<SCRIPT LANGUAGE="JavaScript">
CreateSelect("HwForm","S_1|S_2|S_3","华北地区|山东|济宁","请选择地区@|请选择省份@|请选择城市@",AllStr1,3);
</SCRIPT>
</FORM>

HwForm是表单的名字

而

S_1|S_2|S_3是三个Select表单的名字，如果在js中，可以用doucment.HwForm.S_1.value得到选中的一级的值

如果在asp中，可以用Request("S_3")得到选中的三级值