这个用 onchange怎么实现 最好能帮写一下


<input type="text" id="a" onkeydown="Check()">
<div id="Msg">请输入数字</div>
<script>
function Check()
{
var Value=document.getElementById("a").value;
//正则替换
var reg=/^\d*$/;
if(!reg.test(Value))
{
document.getElementById("Msg").innerText="输入错误";
}
else
{
document.getElementById("Msg").innerText="请输入数字";
}
}</script>

解决方案 »

  1.   

    这就是那个 我改不对了 帮我改下吧 好不 谢谢啦
    <html>
      <head>
        <script type="text/javascript">
          function account(operator)
          {
            var a=document.getElementById("text1").value;
            var b=document.getElementById("text2").value;
     
            if(!isNaN(a) && !isNaN(b))
            {
               if(a==""||b=="")
               {
                 alert("您没有输入数值")
                 return;
               }
            switch(operator)
            {
               case "+":
                 document.getElementById('result').innerHTML=parseFloat(a)+parseFloat(b);
               break;
               case "-":
                 document.getElementById('result').innerHTML=parseFloat(a)-parseFloat(b);
               break;
               case "*":
                 document.getElementById('result').innerHTML=parseFloat(a)*parseFloat(b);
               break;
               case "/":
                 if(parseFloat(b)==0)
                 {
                   alert("除数不能为0")
                   return;
                 }
                 else
                 {
                   document.getElementById('result').innerHTML=parseFloat(a)/parseFloat(b);
                 }
                break;
              }
            }
            else
            {
              if(isNaN(a))
              { 
                document.getElementById("label1").innerHTML = document.getElementById("hidden").value;
                
              }
              else if(isNaN(b))
              { 
                document.getElementById("label2").innerHTML = document.getElementById("hidden").value;
               
              }
            } 
          }
           </script>
        </head>
        <body>
          <form align="center">
             <table align="center" border="1" bordercolor="#FF0000" wridth="90px">
              <tr>
                <td>
                <center><b><h1>四则计算器</h1></b></center>
                </td>
              </tr>
              <tr>
                <td>
                <input type="text"  id="text1" />
                <label id="label1">输入数字</label>
                </td>
              </tr>
              <tr>
                <td>
                <input type="text" id="text2" />
                <label id="label2">输入数字</label>
                <input type="hidden" id="hidden" value="输入错误" >
                </td>
              </tr>
              <tr>
                <td>
                <input type="hidden" id="hidden" value="您输入值非法" />
                <input type="button" name="add"  value=" + " onClick="account('+')">
                <input type="button" name="sub"  value=" - " onClick="account('-')">
                <input type="button" name="mul"  value=" * " onClick="account('*')">
                <input type="button" name="div"  value=" / " onClick="account('/')">
                </td>
              </tr>
              <tr>
                <td>
                 &nbsp;<div id="result" align="center"></div>
                 <input type="hidden" value="您输入了非数字" />
                </td>
              </tr>
              <tr>
                <td>
                <input type="reset" id="Submit" value="重新输入"  align="center"/>
                </td>
              </tr>
             </table>
         </form>
      </body>
    </html>