<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><HTML> <HEAD> <TITLE> Test </TITLE> <script>... function show(obj)...{ if(obj.type=="text")...{ obj.style.display = "none"; document.getElementById('pass').style.display = "block"; document.getElementById('pass').value=""; document.getElementById('pass').focus(); }else...{ var pass = document.getElementById('pass').value; if(pass.length<1)...{ obj.style.display = "none"; document.getElementById('txt').style.display = "block"; } } } </script> </HEAD> <BODY><input id="txt" type="text" value="请输入密码" onfocus="show(this)" style="width:150px;height:20px"><input id="pass" type="password" value="" style="display:none;width:150px;height:20px" onblur="show(this)"><script>...</script> </BODY></HTML> 鼠标点击文本框,此时文本框获得焦点,onfocus事件执行,在js里,将文本框隐藏,显示密码框,同时密码框获得焦点。鼠标离开密码框,如果没有输入密码,则密码框隐藏,文本框显示。