js在表单提交时的验证

第一种：


复制代码代码如下:

<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

复制代码代码如下:

<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：

复制代码代码如下:

<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>