[TOC] # 第一种 ~~~ <script type="text/javascript"> function check(form) { if(form.userId.value=='') { alert("请输入用户帐号!"); form.userId.focus(); return false; } if(form.password.value==''){ alert("请输入登录密码!"); form.password.focus(); return false; } return true; } </script> <form action="login.do?act=login" method="post"> 用户帐号 <input type=text name="userId" size="18" value="" > <br> 登录密码 <input type="password" name="password" size="19" value=""/> <input type=submit name="submit1" value="登陆" onclick="return check(this.form)"> </form> ~~~ # 第二种 ~~~ <script type="text/javascript"> function check(form) { if(form.userId.value=='') { alert("请输入用户帐号!"); form.userId.focus(); return false; } if(form.password.value==''){ alert("请输入登录密码!"); form.password.focus(); return false; } return true; } </script> <form action="login.do?act=login" method="post" onsubmit="return check(this)"> 用户帐号 <input type=text name="userId" size="18" value="" > <br> 登录密码 <input type="password" name="password" size="19" value=""/> <input type=submit name="submit1" value="登陆"> </form> ~~~ # 第三种 ~~~ <script type="text/javascript"> function check(form) { if(form.userId.value=='') { alert("请输入用户帐号!"); form.userId.focus(); return false; } if(form.password.value==''){ alert("请输入登录密码!"); form.password.focus(); return false; } document.myform.submit(); } </script> <form action="login.do?act=login" name="myform" method="post"> 用户帐号 <input type=text name="userId" size="18" value="" > <br> 登录密码 <input type="password" name="password" size="19" value=""/> <input type=button name="submit1" value="登陆" onclick="check(this.form)"> </form> ~~~