方法1：使用form onsubmit标签 return XXX()方法
<!--onsubmit--> <form id="formid" name="myform" method='post' onsubmit="return checkUser();"> <table border="0"> <tr> <td width="60" height="40" align="right">用户名 </td> <td><input type="text" value="" class="text2" name="username" id="userid" /></td> </tr> <tr> <td width="60" height="40" align="right">密 码 </td> <td><input type="password" value="" class="text2" name="userpass" id="userpassid" /></td> </tr> <tr> <td width="60" height="40" align="right"> </td> <td> <div class="c4"> <input type="submit" value="登录" class="btn2"/> </div> </td> </table> </form> <script> function checkUser() { var result = document.getElementById("userid").value; var password = document.getElementById("userpassid").value; if (result == "") { alert("用户名不能为空"); return false; } if (password == "") { alert("密码不能为空"); return false; } } debugger; alert('Your data is correct.'); </script>方法2：input onclick标签
<form id="formid" name="myform" method='post'> <table border="0"> <tr> <td width="60" height="40" align="right">用户名 </td> <td><input type="text" value="" class="text2" name="username" id="userid" /></td> </tr> <tr> <td width="60" height="40" align="right">密 码 </td> <td><input type="password" value="" class="text2" name="userpass" id="userpassid" /></td> </tr> <tr> <td width="60" height="40" align="right"> </td> <td> <div class="c4"> <!--onclick--> <input type="submit" value="登录" class="btn2" onclick="checkUser();"/> </div> </td> </table> </form>转载于:https://www.cnblogs.com/Lulus/p/7873774.html
