表单列表select和option操作

1. 动态创建select

function createSelect() {
      var mySelect = document.createElement("select");
            mySelect.id = "mySelect";
            document.body.appendChild(mySelect);
}

2.添加选项option

function addOption() {
              var s = document.getElementById("mySelect");
            s.add(new Option("text", "value"))//IE
            s.options.add(new Option("text", "value"));firefox
}

3.删除所有optiong和指定的option

  function remove() {
        var obj = document.getElementById("mySelect);
        obj.options.length = 0;
//删除指定
      var index = obj.selectedIndex;
      ob.optionsj.remove(index);
}

4.获取option的文本和值

function val() {
      var obj = document.getElementById("mySelect");

      var index = obj.selectedIndex;
      var text = obj.optiosn[index].text;
      var value = ojb.options[index].value;
}

注意，可以使用obj.selectedIndex != -1来判断选项是否被选中;