from表单数据的合法性验证是个很常见的需求，jQuery提供了一个插件：jquery validate 官网下载。
若想使用需先引用jquery.validate.js，并且要在jquery.js之后引用。
<script src="//cdn.bootcss.com/jquery/3.4.1/jquery.js"></script><script src="js/jquery.validate.js"></script> 把现在写的项目拿来演示一下，其使用了bootstrap框架。
$(function() { jQuery.validator.addMethod("regUserName", function(value, element) { return this.optional(element) || /^[0-9]*[a-zA-Z_u4e00-u9fa5]+[0-9]*$/.test(value); }, "注册昵称为4-10位数字、下划线、中文或英文字母，但不能全是数字"); jQuery.validator.addMethod("isMobile", function(value, element) { var length = value.length; var mobile = /^(((d{2,3}))|(d{3}-))?1[3,8,5]{1}d{9}$/; return this.optional(element) || (length == 11 && mobile.test(value)); }, "请正确填写您的手机号码"); //登录帐号合法性验证 jQuery.validator.addMethod("logAccountCheck", function (value, element) { var length = value.length; var mobile = /^(((d{2,3}))|(d{3}-))?1[3,8,5]{1}d{9}$/; return this.optional(element) || (length == 11 && mobile.test(value)) || /^[u0391-uFFE5w]+$/.test(value); }, "昵称不符合登录规则");$("#fillForm").validate({ errorElement: \'span\', errorClass: \'help-block\', focusInvalid: false, rules: { new_userName: { required: true, regUserName: true, minlength: 4, maxlength: 10 }, new_userPwd: { required: true, rangelength: [5, 15] }, new_userPwd_twice: { required: true, equalTo: "#new_userPwd" }, new_userEmail: { required: true, email: true }, new_userPhone: { required: true, isMobile:true, digits: true, minlength: 11, maxlength: 11 }, new_userBirth: { required: true }, new_userCollege: { required: true }, new_userMajor: { required: true } }, messages: { new_userName: { required: \'昵称不能为空\', minlength: \'昵称最少为4位\', maxlength: \'昵称最多为10位\' }, new_userPwd: { required: \'密码不能为空\', rangelength: $.validator.format("密码长度必须在 {0} 到 {1} 之间") }, new_userPwd_twice: { required: \'此项不能为空\', equalTo: \'两次输入的密码必须一致\' }, new_userEmail: { required: \'邮箱不能为空\', email: \'邮箱格式不正确(例如: xxx@xx.com)\' }, new_userPhone: { required: \'电话号不能为空\', digits: \'电话号必须是数字\', minlength: \'电话号为11位\', maxlength: \'电话号为11位\' }, new_userBirth: { required: \'生日不能为空\' }, new_userCollege: { required: \'学院不能为空\' }, new_userMajor: { required: \'专业不能为空\' } }, highlight: function (element) { $(element).closest(\'.form-group\').addClass(\'has-error\'); }, success: function (label) { label.closest(\'.form-group\').removeClass(\'has-error\').addClass(\'has-success\'); label.remove(); }, errorPlacement: function (error, element) { element.parent(\'div\').after(error); }, submitHandler: function (form) { var result = { "new_userName": $("#new_userName").val(), "new_userPwd": $("#new_userPwd").val(), "new_userEmail": $("#new_userEmail").val(), "new_userPhone": $("#new_userPhone").val(), "new_userBirth": $("#new_userBirth").val(), "new_userGender": $("input[name=\'new_userGender\']:checked").val(), "new_userCollege": $("#new_userCollege").val() + \',\' + $("#new_userMajor").val() }; result.new_userIP = ip; var res = JSON.stringify(result); alert(res); return false; } })}) html文件跟平常一样，主要在js中进行验证：
$(function() { jQuery.validator.addMethod("regUserName", function(value, element) { return this.optional(element) || /^[0-9]*[a-zA-Z_u4e00-u9fa5]+[0-9]*$/.test(value); }, "注册昵称为4-10位数字、下划线、中文或英文字母，但不能全是数字"); jQuery.validator.addMethod("isMobile", function(value, element) { var length = value.length; var mobile = /^(((d{2,3}))|(d{3}-))?1[3,8,5]{1}d{9}$/; return this.optional(element) || (length == 11 && mobile.test(value)); }, "请正确填写您的手机号码"); //登录帐号合法性验证 jQuery.validator.addMethod("logAccountCheck", function (value, element) { var length = value.length; var mobile = /^(((d{2,3}))|(d{3}-))?1[3,8,5]{1}d{9}$/; return this.optional(element) || (length == 11 && mobile.test(value)) || /^[u0391-uFFE5w]+$/.test(value); }, "昵称不符合登录规则");$("#fillForm").validate({ errorElement: \'span\', errorClass: \'help-block\', focusInvalid: false, rules: { new_userName: { required: true, regUserName: true, minlength: 4, maxlength: 10 }, new_userPwd: { required: true, rangelength: [5, 15] }, new_userPwd_twice: { required: true, equalTo: "#new_userPwd" }, new_userEmail: { required: true, email: true }, new_userPhone: { required: true, isMobile:true, digits: true, minlength: 11, maxlength: 11 }, new_userBirth: { required: true }, new_userCollege: { required: true }, new_userMajor: { required: true } }, messages: { new_userName: { required: \'昵称不能为空\', minlength: \'昵称最少为4位\', maxlength: \'昵称最多为10位\' }, new_userPwd: { required: \'密码不能为空\', rangelength: $.validator.format("密码长度必须在 {0} 到 {1} 之间") }, new_userPwd_twice: { required: \'此项不能为空\', equalTo: \'两次输入的密码必须一致\' }, new_userEmail: { required: \'邮箱不能为空\', email: \'邮箱格式不正确(例如: xxx@xx.com)\' }, new_userPhone: { required: \'电话号不能为空\', digits: \'电话号必须是数字\', minlength: \'电话号为11位\', maxlength: \'电话号为11位\' }, new_userBirth: { required: \'生日不能为空\' }, new_userCollege: { required: \'学院不能为空\' }, new_userMajor: { required: \'专业不能为空\' } }, highlight: function (element) { $(element).closest(\'.form-group\').addClass(\'has-error\'); }, success: function (label) { label.closest(\'.form-group\').removeClass(\'has-error\').addClass(\'has-success\'); label.remove(); }, errorPlacement: function (error, element) { element.parent(\'div\').after(error); }, submitHandler: function (form) { var result = { "new_userName": $("#new_userName").val(), "new_userPwd": $("#new_userPwd").val(), "new_userEmail": $("#new_userEmail").val(), "new_userPhone": $("#new_userPhone").val(), "new_userBirth": $("#new_userBirth").val(), "new_userGender": $("input[name=\'new_userGender\']:checked").val(), "new_userCollege": $("#new_userCollege").val() + \',\' + $("#new_userMajor").val() }; result.new_userIP = ip; var res = JSON.stringify(result); alert(res); return false; } })}) 简单用法：
1.：rules里定义输入框规则，常见的有required, minlength, maxlength, email, 其中使用输入框的name属性来指定输入框。
2：messages里定义当输入内容不符合规则时显示的信息，如果自定义则显示默认的错误信息。
3：可以自定义规则，比如上面代码开头部分定义了自定义规则，可以根据自己的需求仿照代码即可，而且网上也提供了现成的自定义验证规则。
4：当输入框均符合规则时，可以点击提交，此时，会指定submitHandler函数。
