1.概念

<select id="mineType2"  onChange="getChild(this,1)">
  <option value ="volvo">Volvo</option>
  <option value ="saab">Saab</option>
  <option value="opel">Opel</option>
  <option value="audi">Audi</option>
</select>

<select&> 元素中的 <option> 标签用于定义列表中的可用选项。

2.jq获取select选中值

var value=$("select option:selected").val()

或者

var value=$("select option:selected").text()

3.jq将动态获取的值设置为选中状态

$(".rs-club option:selected").text("xxx");

4.设置select可以选择

 $("#mineType2").removeAttr("disabled");

5.设置select不可以选择

    $("#mineType2").attr("disabled", "disabled");

6.jqery 添加

 $("#cengWei").append("<option selected='selected' value='" + a.cengWei + "'>" + a.cengWei + "</option>");

===============================================
 var obj=document.getElementById('mineType'); 
obj.options.add(new Option("请选择矿区",""));
obj.options.add(new Option("色连二矿","selian2"));
obj.options.add(new Option("泊江海子","bojianghaizi"));
obj.options.add(new Option("唐家会","tangjiahui"));
obj.children[3].selected=true;

7.juery 设置选择项

var selectid_cengwei = document.getElementById("cengWei");
      for (i = 0; i < selectid_cengwei.length; i++) {
        if (selectid_cengwei[i].text == a.cengWei)
        selectid_cengwei[i].selected = true;
      }

8.二级联动

function getChild(currFylx) {
     //当前 所选择 的费用类型
      // var currFylx_value = currFylx.options[currFylx.selectedIndex].value;
      var mine_type = $("#mineType2 option:selected");
      var select_mine_type = mine_type.val();
      var data = {}
      // data["jiance_danyuan"]=currFylx_value
      $.ajax({
        url: '/wz_get_workname/' + select_mine_type,
        type: 'GET',
        async:false,
        dataType: 'JSON',
        success: function (data) {
          console.log(data);
          var obj2 = document.getElementById('jianCeDanYuan');
          var cengWei = document.getElementById('cengWei');
          $("#jianCeDanYuan").html("");
          $("#cengWei").html("");
          cengWei.options.add(new Option("请选择", "请选择"));
          obj2.options.add(new Option("请选择", "请选择"));
          for (var i = 0; i < data.length; i++) {
            obj2.options.add(new Option(data[i].workName, data[i].workName));
          }
        }
      });
    }