js表单的获取方法

js中获取表单对象的方法   <input   type=”text” /> 

 HTML部分

  <form action="" name="form1" id="frm1" method="post">

            <input type="text" value="请输入用户名" name="number" id="number" ><br />

            <input type="button" value="提交"  onclick="checkForm()">

    </form>

JS部分

方法1:

<script>

        funciton checkForm(){

        var obj=document.getElementById("number");

        alert(obj.value)

       }

</script>

方法2:

  <form id ="form1" action="test.do" method="post">
    <input type="text" name="a" value="1">
    <br>
    <input type="text" name="a" value="2">
    <br>
    <input type="text" name="a" value="3">
    <br>
    <input  type="submit" value="提交">
   </form> 

 </body>
  <script type="text/javascript">
         document.getElementById('form1').onsubmit=function(){
         var as=document.getElementsByName('a');  //数组
       for(i=0;i<as.length;i++){
        alert(as[i].value);
        }
     }
    </script>

方法3:

<script>

        funciton checkForm(){

             var obj=document.form1.number.value;

             var obj=document.forms[0].number.value;

             var obj=document.forms[0]['number'].value;

             var obj=document.form1['number'].value;

       }

</script>