JavaScript实现三级联动菜单效果_JavaScript

JavaScript实现三级联动菜单效果

三级联动考察的应该是对于数据的处理，只要清楚其中的关系，再多几级都是一样的：

html部分：

<!doctype html>
<html>
<head>
  <meta charset="utf-8" />
  <title>3级联动菜单</title>
  <script>
    var region = {
      广东:
      {
        "广州":["广州1","广州2","广州3"],

        "珠海":["珠海1","珠海2","珠海3"],

        "佛山":["佛山1"]
      },
      湖南:
      {
        "常德":["石门","桃源","临澧","汉寿"],

        "益阳":["益阳1","益阳2","益阳3"]
      }
    }
  </script>
</head>
  <body>

    <select id="province" onchange="change(this.value);">
      <option>请选择省份</option>
    </select>

    <select id="city" onchange="countychange(this.value);">
      <option>请选择地市</option>
    </select>

    <select id="county">
      <option>请选择县城</option>
    </select>
  <script src='test.js'></script>
  </body>
</html>

js部分：

var province = document.queryselector("#province");
  var city = document.queryselector("#city");
  var county = document.queryselector("#county");
  //二级联动不用定义你选的省份,直接用省份(key)来决定下面的市(value)值
  var provincename = null;

  for (ele in region){
    var op = new option(ele , ele , false , false); //new option("文本","值",true,true).后面两个true分别表示默认被选中和有效
    //console.log(op);
    province.options[province.length] = op;
  }

  var change = function(src){
    city.innerhtml = "";
    if(src === '请选择省份'){
      var op = new option('请选择地市' , '请选择地市' , false , false);
      city.options[0] = op;
    }else{
      for (index in region[src]){
        //console.log(index);
        var op = new option(index , index , false , false);
        city.options[city.length] = op;
      }
    }
    //记住选择省份的值
    provincename=src;
    countychange(city.value)
  }

  var countychange = function(src2){
    county.innerhtml = "";
    if(src2 === '请选择地市'){
      var op = new option('请选择县城','请选择县城', false , false);
      county.options[0] = op;
    }else{
      for (index in region[provincename][src2]){
        //console.log(index);
        var op = new option(region[provincename][src2][index] , region[provincename][src2][index] , false , false);
        county.options[county.length] = op;
      }
    }
  }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持移动技术网。