<body>
<select id="s1"><option>-请选择-</option></select>
<select id="s2"><option>-请选择-</option></select>
<select id="s3"><option>-请选择-</option></select>
<script>
var arr1=["黑龙江省",'吉林省','北京'];
var arr2=[
['哈尔滨','讷河','黑河'],
['长春','吉林市','白城'],
['海淀区','朝阳区','房山']
];
var arr3=[
[['香房','动力','道里'],['讷河1','讷河2','讷河3'],['黑河1','黑河2','黑河3']],
[['长春1','长春2','长春3'],['吉林市1','吉林市2','吉林市3'],['白城1','白城2','白城3']],
[['海淀区1','海淀区1','海淀区1'],['朝阳区1','朝阳区1','朝阳区1'],['房山1','房山2','房山3']],
];
function $(id){
return document.getElementById(id);
}
function superMan(arr,ele){
for(var i=0;i<arr.length;i++ ){
var option=document.createElement('option');
option.innerHTML=arr[i];
option.value=i;
ele.appendChild(option);
}
}
window.onload=function (){
var s1=$('s1');
s1.onchange=changeCity;
while(s1.children.length>1){
s1.removeChild(s1.lastElementChild);
}
superMan(arr1,s1);
}
var n=null;//索引
function changeCity(){
var s2=$('s2');
s2.onchange=changeQu;
while(s2.children.length>1){
s2.removeChild(s2.lastElementChild);
}
n=this.value;//索引
var ar=arr2[n];
superMan(ar,s2);
}
function changeQu(){
var s3=$('s3');
while(s3.children.length>1){
s3.removeChild(s3.lastElementChild);
}
var arrr=arr3[n][this.value];
console.log(arrr);
superMan(arrr,s3);
}
</script>
</body>
我想知道var arrr=arr3[n][this.value];的含义，以及各个步骤的大概意思
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