Two methods are used to link drop-down boxes in traditional HTML pages:
1) Directly hardcode the content in the drop-down box into the javascript of html, and call the Javascript function to write it into the drop-down box in a loop. This method is not suitable for situations where the contents of the drop-down box change frequently. Because the data source and JavaScript program are written on the same page.
<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 reads the database directly, takes the records in the database and writes them into JavaScript, and then, like the first method, calls the JavaScript function to write to the drop-down box in a loop. This method separates the data source from JavaScript, but exposing the database connection has little practical value from a security perspective.
My method is to put the data in the drop-down box in an xml file, use javascript to read the XML file, and obtain the content in the drop-down box.
The HTML file is as follows:
<!-- 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 deleteOption() {
}
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="95788主叫卡">
<subclass display_name="1152069589-1152069638">dangdang1</subclass>
<subclass display_name="1152081031-1152081080">dangdang2</subclass>
<subclass display_name="1152547201-1105254750">dangdang3</subclass>
<subclass display_name="1152548401-1152548700">dangdang4</subclass>
<subclass display_name="1152548701-1152549000">dangdang5</subclass>
<subclass display_name="1156000001-1156010000">dangdang6</subclass>
</class>
<class display_name="网上注册">
<subclass display_name="1152000001-1152001000">zhuce_user1</subclass>
<subclass display_name="1151001000-1151005000">zhuce_user2</subclass>
</class>
<class display_name="通讯">
<subclass display_name="1156030001-1156080000">tongxun</subclass>
</class>
</item>This method separates the data source from the javascript program and is suitable for frequently changing data sources. In xmlDoc.load, you can directly call URL parameters and read remote XML to achieve loose coupling. The above application passes in IE6.0. The disadvantage is that when removing the contents of the drop-down box list, you need to
repeat the deletion operation, otherwise there will be obvious bugs. I hope some readers can correct me.
The above is the detailed explanation of Javascript calling XML to create a linked drop-down box code example. For more related content, please pay attention to the PHP Chinese website (m.sbmmt.com)!
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