​x
 
<html>
<head>
<script type="text/javascript" src="/jquery/jquery.js"></script>
<script type="text/javascript">
$(document).ready(function(){
  $("button").click(function(){
    $("input:text").val(function(n,c){
      return c + " Gates";
    });
  });
});
</script>
</head>
​
<body>
<p>Name: <input type="text" name="user" value="Bill" /></p>
<button>设置文本域的值</button>
</body>
</html>
​