The example in this article describes how to implement cascading menus in JavaScript. Share it with everyone for your reference. The specific implementation method is as follows:
<html>
<head>
<title>test</title>
<script type="text/javascript">
function f()
{
var sel=document.getElementById("country");
var sel2=document.getElementById("city");
var cnarr1=new Array("bj","sh")
var cnarr2=new Array("beijing","shanghai")
var usaarr1=new Array("dc","ny")
var usaarr2=new Array("Washington","NewYork")
for(var i=sel2.length;i>=0;i--){
sel2.removeChild(sel2.childNodes[i]);
}
var op=document.createElement("option");
op.value="please";
op.text="please";
sel2.appendChild(op);
if(sel.value=='USA'){
for(i=0;i<2;i++){
op.value=usaarr1[i];
op.text=usaarr2[i];
sel2.appendChild(op);
}
}
else if(sel.value=='CN'){
for(i=0;i<2;i++){
op.value=cnarr1[i];
op.text=cnarr2[i];
sel2.appendChild(op);
}
}
}
</script>
</head>
<body>
<select onchange="f()" id='country'>
<option >please</option>
<option value='USA'>America</option>
<option value='CN'>China</option>
</select>
<select id='city'>
<option >please</option>
</select>
</body>
</html>
I hope this article will be helpful to everyone’s JavaScript programming design.
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
