传统的HTML页面中连动下拉框采用了两种方法:1)直接将下拉框中的内容hardcode于html的javascript中,调用javascript函数循环写入下拉框中。这种方法不适用于下拉框内容经常改变的情况。因为数据源和javascript程序写死在同一页面。List

传统的HTML页面中连动下拉框采用了两种方法:

1)直接将下拉框中的内容hardcode于html的javascript中,调用javascript函数循环写入下拉框中。这种方法不适用于下拉框内容经常改变的情况。因为数据源和javascript程序写死在同一页面。

<html>

<head>

<title>List</title>

<meta http-equiv="Content-Type" content="text/html; c

harset=gb2312">

<script LANGUAGE="javascript">

<!--

var onecount;

onecount=0;

subcat = new Array();

subcat[0] = new Array("徐汇区","01","001");

subcat[1] = new Array("嘉定区","01","002");

subcat[2] = new Array("黄浦区","01","003");

subcat[3] = new Array("南昌市","02","004");

subcat[4] = new Array("九江市","02","005");

subcat[5] = new Array("上饶市","02","006");

onecount=6;

function changelocation(locationid)

{

document.myform.smalllocation.length = 0;

var locationid=locationid;

var i;

document.myform.smalllocation.options[0] = new Option('====所有地区====','');

for (i=0;i <onecount; i++)

{

if (subcat[i][1] == locationid)

{

document.myform.smalllocation.options[document.myform.smalllocation.length]

= new Option(subcat[i][0], subcat[i][2]);

}

}

}

//-->

</script>

</head>

<body>

<form name="myform" method="post">

<select name="biglocation"

onChange="changelocation(document.myform.biglocation.options[document.myform.biglocation.selectedIndex].value)">

<option value="01" selected>上海</option>

<option value="02">江西</option>

</select>

<select name="smalllocation">

<option selected value="">==所有地区==</option>

</select>

</form>

<script LANGUAGE="javascript">

<!--

changelocation(document.myform.biglocation.options[document.myform.biglocation.selectedIndex].value);

//-->

</script>

</body>

</html>

2)javascript 直接读取数据库,取数据库中的记录写入javascript中,然后和第一种方法一样,调用javascript函数循环写入下拉框中。此方法将数据源与javascript分开,但,公开数据库的连接,从安全角度说,没有多少实用价值。

我的方法是将下拉框中的数据放在XML文件中,用javascript读XML文件,取得下拉框中的内容。

HTML 文件如下:

<!-- myfile.html -->

<html>

<head>

<script language="JavaScript" for="window" event="onload">

var xmlDoc = new ActiveXObject("Microsoft.XMLDOM");

var i=0;

var j=0;

var subclass_name="";

loadXML();

function loadXML(){

xmlDoc.async="false";

xmlDoc.load("account.xml");

xmlObj=xmlDoc.documentElement;

nodes = xmlDoc.documentElement.childNodes;

document.frm.mainclass.options.length = 0;

document.frm.subclass.options.length = 0;

for (i=0;i<xmlObj.childNodes.length;i++){

labels=xmlObj.childNodes(i).getAttribute("display_name");

values=xmlObj.childNodes(i).text;

document.frm.mainclass.add(document.createElement("OPTION"));

document.frm.mainclass.options[i].text=labels;

document.frm.mainclass.options[i].value=values;

}

}

</script>

<script language="JavaScript" >

var xmlDoc = new ActiveXObject("Microsoft.XMLDOM");

var i=0;

var j=0;

function setsubclass(main){

var is_selected="N";

if (document.frm.subclass.options.length!=0) {

for (i=0;i<=document.frm.subclass.options.length;i++)

document.frm.subclass.options[i]=null ;

}

//重复才有效

if (document.frm.subclass.options.length!=0) {

for (i=0;i<=document.frm.subclass.options.length;i++){

document.frm.subclass.options[i]=null ;

document.frm.subclass.options.remove(i);

}

}

for (i=0;i<xmlObj.childNodes.length;i++){

var values="";

var lables="";

if (is_selected=="Y") return;

labels=xmlObj.childNodes(i).getAttribute("display_name");

values=xmlObj.childNodes(i).text;

//alert(labels+ " | "+main);

if (labels==main){

is_selected="Y";

for (j=0;j<xmlObj.childNodes(i).childNodes.length;j++){

//subclass_name="document.frm.subclass";

labels=xmlObj.childNodes(i).childNodes(j).getAttribute("display_name");

values=xmlObj.childNodes(i).childNodes(j).text;

//alert(values);

document.frm.subclass.add(document.createElement("OPTION"));

document.frm.subclass.options[j].text=labels;

document.frm.subclass.options[j].value=values;

}

}

}

}

</script>

<title>在HTML中调用XML数据</title>

</head>

<body bgcolor="#FFFFFF">

<FORM NAME="frm">

类型<SELECT NAME="mainclass" OnChange='setsubclass(this[selectedIndex].text)'></SELECT>

<option selected value="" ></option>

子类<SELECT NAME="subclass"></SELECT>

</form>

</body>

</html>

account.xml 如下:

<?xml version="1.0" encoding="gb2312"?>

<item>

<class display_name="未选定">

<subclass display_name="">Not Available</subclass>

</class>

<class display_name="推荐网站">

<subclass display_name="看上去很美">www.7say.com</subclass>

<subclass display_name="移动互联">www.xj139.com</subclass>

<subclass display_name="众信实业">www.xjzxsy.com</subclass>

</class>

<class display_name="门户网站">

<subclass display_name="新浪">www.sina.com</subclass>

<subclass display_name="搜狐">www.sohu.com</subclass>

</class>

<class display_name="其它网站">

<subclass display_name="蓝色理想">www.blueidea.com</subclass>

</class>

</item>