JavaScript常用表单验证
function addUser() {var userIdField = document.getElementById("userId");var userNameField = document.getElementById("userName");var passWordField = document.getElementById("password");var contactTelField = document.getElementById("contactTel");//用户代码不能为空if (trim(userIdField.value) == "") {alert("请输入用户代码！");userIdField.focus();return;}//用户代码的长度不能小于四个字符if ((trim(userIdField.value).length < 4)) {alert("用户代码的长度至少为4个！");userIdField.focus();return;}//用户代码首字符必须为字母if (!(trim(userIdField.value).charAt(0) >= 'a' && trim(userIdField.value).charAt(0) <= 'z')) {alert("首字符必须为字母！");userIdField.focus();return;}//使用正则表达式验证用户名只能为4~6位var re = new RegExp(/^[a-zA-z0-9]{4,6}$/);if (!re.test(trim(userIdField.value))) {alert("用户代码必须为数字或字母，只能为4~6位！");userIdField.focus();return;}//用户名称不能为空if (trim(userNameField.value) == "") {alert("请输入用户名称！");userNameField.focus();return;}//用户密码不能为空if (trim(passWordField.value) == "") {alert("用户密码不能为空！");passWordField.focus();return;}//普通方案验证手机只能为数字if (trim(contactTelField.value) != "") {for ( var i = 0; i < trim(contactTelField.value).length; i++) {var chrNum = trim(contactTelField.value).charAt(i);if (!(chrNum >= '0' && chrNum <= '9')) {alert("联系电话只能为数字！");return;}}}//提交表单with(document.getElementById("userForm")){action="user_add.jsp";method="post";submit();}}//用户代码只允许输入字母，不允许输入其它function userIdOnKeyPress() {if (!(window.event.keyCode >= '97' && window.event.keyCode <= '122')) {window.event.keyCode=0;}}//按回车键进行换行，到button键时停止function document.onkeydown(){if(window.event.keyCode=='13' && window.event.srcElement.type!='button'){window.event.keyCode='9';}?