在文本框中显示 请输入什么信息

    <script type="text/javascript" language="javascript">
        var txtTrain=document.getElementById("txtXianlu");
        function searchclearInfoJs(obj){
         if(txtTrain.value=="输入地点或车次" && obj==0)
         {
          txtTrain.style.color="#000";
          txtTrain.value="";
         }
        }
        function searchinputInfoJs(obj){
         if(txtTrain.value=="" && obj==0){
          txtTrain.style.color="#999";
          txtTrain.value="输入地点或车次";
         }
        }
        if(txtTrain!=undefined){
         if(txtTrain.value==""||txtTrain.value=="输入地点或车次")
         {
          txtTrain.style.color="#999";
          txtTrain.value="输入地点或车次";
          txtTrain.onfocus=function(){
          searchclearInfoJs(0);
          }
          txtTrain.onblur=function(){
          searchinputInfoJs(0);
          }
         }
        }
    </script>

 

 

在form后面写