jsp怎么在输入框中写默认提示信息

jsp怎么在输入框中写默认提示信息，当光标点击输入框时，提示信息消失，可供输入。弱输入框中为空，光标离去，默认提示信息又出现
效果类是于ExtJs的emptyText效果
JSPinput输入框提示

解决方案 »

  1.   

    $(function(){

    var n = $('#name');
    n.val('请输入姓名');
    n.focus(function(){
    $(this).val('');
    }).blur(function(){
    $(this).val('请输入姓名');
    })

    });
      

  2.   

    jquery 获得焦点focus  失去焦点 blur
    javascript 获得焦点onfocus  失去焦点 onblur
      

  3.   

    query 获得焦点focus  失去焦点 blur
    javascript 获得焦点onfocus  失去焦点 onblur
      

  4.   

    最后是用的这个方法实现了效果
    代码供参考：
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
     <html xmlns="http://www.w3.org/1999/xhtml">
         <head>
             <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
             <title>huangwei </title>
             <script type="text/javascript">
                 //onclick="alert(this.innerText)"
             function labelClick(){ 
                 var username=document.getElementsByName("username")[0]; 
                 var myLabel = document.getElementById("mylabel"); 
                 if(username.value==""){ 
                     myLabel.className="block3";//italic 
                 } 
                 username.focus(); 
             } 
             function TextKeyUp(){ 
                 var myLabel = document.getElementById("mylabel"); 
                 var username = document.getElementsByName("username")[0]; 
                 if (username.value == "") { 
                     myLabel.style.zIndex = 0; 
                     myLabel.className="block3";//italic 
                 } 
                 else { 
                 myLabel.style.zIndex = -2; 
                 } 
             } 
             function TextKeydown(){ 
                 var myLabel = document.getElementById("mylabel"); 
                 myLabel.style.zIndex = -2; 
             } 
             function TextFocus(){ 
                 var myLabel = document.getElementById("mylabel"); 
                 var username = document.getElementsByName("username")[0]; 
                 if(username.value==""){ 
                     myLabel.style.zIndex = 0; 
                     myLabel.className="block3";//italic 
                 }else{ 
                     myLabel.style.zIndex = -2; 
                 } 
             } 
             function TextBlur(){ 
                 var myLabel = document.getElementById("mylabel"); 
                 var username = document.getElementsByName("username")[0]; 
                 if(username.value==""){ 
                     myLabel.style.zIndex = 0; 
                     myLabel.className="block2"; 
                 } 
             } 
             </script>
             <style type="text/css">
                 .block1{ 
                     width:50xp; 
                     height:20px; 
                     padding:10px; 
                     margin:5px; 
                     background-color:#ffffff; 
                                     position:absolute; 
                     left:15px; 
                     top:30px; 
                     z-index:-1; 
              
                 } 
                 .block2{ 
                     width:50xp; 
                     height:16px; 
                     padding:10px; 
                     margin:5px; 
                     background-color:#ffffff; 
                                     position:absolute; 
                     left:20px; 
                     top:32px; 
                     font-weight:bolder; 
                     color:#ACA899; 
                     font-style:normal; 
                     z-index:0; 
          
                 } 
                 .block3{ 
                     width:50xp; 
                     height:16px; 
                     padding:10px; 
                     margin:5px; 
                     background-color:#ffffff; 
                                     position:absolute; 
                     left:20px; 
                     top:32px; 
                     color:#7e7e7e; 
                     font-style:italic; 
                     z-index:0; 
                 }                             
             </style>
         </head>
         <body>
             <input type="text" name="username" class="block1" onkeyup="TextKeyUp();" onkeydown="TextKeydown();" onfocus="TextFocus();" onblur="TextBlur();" />
             <label id="mylabel" class="block2" onclick="labelClick()" />
                 请输入用户名 
             </label>
         </body>
     </html>