鼠标一点 文字消失 的有关问题

鼠标一点 文字消失 的问题
请问大大们，如果鼠标一点文本框 文本框的默认值 就消失了，然后鼠标点别的地方，文本框又会自动显示默认值，这种效果该怎么做？
我上网搜了很多，用javascript写的，或者是onclick,onblur之类的我都试过，如果是纯html是可以用，但是写在php里面就一点作用都没有！这很奇怪啊！为什么？
代码如下：

JScript code

<!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
http://www.CodeHighlighter.com/

-->
<script language="JavaScript" type="text/javascript">
   function addListener(element,e,fn){    
        if(element.addEventListener){    
             element.addEventListener(e,fn,false);    
         } else {    
             element.attachEvent("on" + e,fn);    
          }    
   }
   var txt_oldPsw = document.getElementById("txt_oldPsw");
   addListener(txt_oldPsw,"click",function(){txt_oldPsw.value = "";})
   addListener(txt_oldPsw,"blur",function(){txt_oldPsw.value = "old Password";})

   var txt_newPsw = document.getElementById("txt_newPsw");
   addListener(txt_newPsw,"click",function(){txt_newPsw.value = "";})
   addListener(txt_newPsw,"blur",function(){txt_newPsw.value = "new Password";})

   var txt_reenter = document.getElementById("txt_reenter");
   addListener(txt_reenter,"click",function(){txt_reenter.value = "";})
   addListener(txt_reenter,"blur",function(){txt_reenter.value = "re-enter new password";})
</script>

登录后复制

PHP code

<!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
http://www.CodeHighlighter.com/

-->
echo "<tr><td><input class='txt_style' id='txt_oldPsw' style='font-size:10.5pt; color:#6b6b6b' type='text' name='txt_oldPsw' value='old password'  $psw_disable></td></tr>";
    
    echo "<tr><td><input class='txt_style' id='txt_newPsw' style='font-size:10.5pt; color:#6b6b6b' type='text' name='txt_newPsw' value='new password' $psw_disable></td></tr>";
    
    echo "<tr><td><input class='txt_style' id='txt_reenter' style='font-size:10.5pt; color:#6b6b6b' type='text' name='txt_reenter' value='re-enter new password' $psw_disable></td></tr>";
    
    echo "<tr><td><input class='btn_active' type='submit' name='$btn_active_define' value='$btn_active_text'></td></tr>";

登录后复制