获取表单select域的选择部分的文本

 body>
 <form action="index.php">
     <select name="" id="select">
         <option value="1">一</option>
         <option value="2">二</option>
         <option value="3">三</option>
     </select>
 </form>
 <script>
     window.onload=function () {
         var select=document.getElementById('select');
         select.onchange=function (ev) {
             console.log(this.options[this.selectedIndex].text);
         }
     }
 </script>
 </body>