级联-city

<!DOCTYPE html>
<html>
 <head>
  <meta charset="UTF-8">
  <title>城市注册</title>
 </head>
 <body>
  省份
  <select name="sf">
   <option value="s1">请选择</option>
  </select>
  城市
  <select name="cs" onclick="choose()">
   <option value="c1">请选择</option>
  </select>
 </body>
 <script type="text/javascript">
  var sf=["请选择","辽宁省","吉林省","黑龙江省"];
  var cs=[["请选择"],["沈阳市","大连市","鞍山市","抚顺市"],["长春市","吉林市","白山市"],["哈尔滨市","大庆市","牡丹江市"]];
  var sfselect=document.querySelector("select");
  var csselect=document.querySelector("select[name='cs']");
  for(var i=0;i<sf.length;i++){
    var option=document.createElement("option");
    option.innerHTML=sf[i];
    option.value=i;
    sfselect.appendChild(option);
   } 
  function choose(){
   csselect.innerHTML="";
   for(var i=0;i<cs[sfselect.value].length;i++){
    var option=document.createElement("option");
    option.innerHTML=cs[sfselect.value][i];
    option.value=i;
    csselect.appendChild(option);
   } 
  }
  
 </script>
</html>