简单的表单验证
html结构
<!-- validata.html --> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Validata</title> </head> <body> <form> <label for="username">账号：</label><input type="text"><br> <label for="password">密码：</label><input type="password"><br> <label for="phonenum">手机：</label><input type="text"><br> <input type="button" value="提交"> </form> <p></p> <script src="https://www.jb51.net/validata.js"></script> </body> </html>
首先先简单地实现以下这个功能
之后再用设计模式丰满
// validata.js var form = document.getElementById('form'), warn = document.getElementById('warn'); var validata = function(){ if(form.username.value === ''){ return warn.textContent = '账号不能为空'; } if(form.password.value === ''){ return warn.textContent = '密码不能为空'; } if(form.phonenum.value === ''){ return warn.textContent = '手机号不能为空'; } var msg = { username: form.username.value, password: form.password.value, phonenum: form.phonenum.value } //ajax('...', msg); ajax提交数据略 return warn.textContent = '用户信息已成功提交至服务器'; } form.submit.onclick = function(){ validata(); }
然后分析以下代码
validata这个函数毫无复用性可言，除此之外存在两个问题
函数同时承担了验证和提交两个职责，违背单一职责原则
验证功能扩展性差，要想添加验证规则就必须深入函数内部，违反开放-封闭原则
所以我们需要对此进行改进
装饰模式重构
先来用装饰模式解决一下函数多职责问题
方法也很简单
改进一下AOP前置装饰函数（Function.prototype.before）
当扩展函数（beforeFn）返回false则不执行当前函数
然后令表单验证函数成为表单提交函数的前置装饰
这样提交前就会进行验证，若验证失败，就不会提交数据
var form = document.getElementById('form'), warn = document.getElementById('warn'); Function.prototype.before = function(beforeFn){ var self = this; return function(){ if(beforeFn.apply(this, arguments) === false) return; return self.apply(this, arguments); } }//改进的AOP前置装饰函数 var validata = function(){ if(form.username.value === ''){ warn.textContent = '账号不能为空'; return false; } if(form.password.value === ''){ warn.textContent = '密码不能为空'; return false; } if(form.phonenum.value === ''){ warn.textContent = '手机号不能为空'; return false; } } var submitMsg = function(){ //将提交的功能从validata函数中提取出来 var msg = { username: form.username.value, password: form.password.value, phonenum: form.phonenum.value } //ajax('...', msg); return warn.textContent = '用户信息已成功提交至服务器'; } submitMsg = submitMsg.before(validata); //让表单验证函数成为表单提交函数的装饰者 form.submit.onclick = function(){ submitMsg(); };
策略模式重构
下面就该解决函数缺乏弹性的问题
使用策略模式就需要有策略对象/类和环境对象/类
毫无疑问策略对象中就应该装着校验规则
又考虑到页面可能不止有一个验证表单
最好写成工厂-类的形式
完整代码如下
var form = document.getElementById('form'), warn = document.getElementById('warn'); Function.prototype.before = function(beforeFn){ var self = this; return function(){ if(beforeFn.apply(this, arguments) === false) return; return self.apply(this, arguments); } } var vldStrategy = { //策略对象-验证规则 isNonEmpty: function(value, warnMsg){ //输入不为空 if(value === '') return warnMsg; }, isLongEnough: function(value, length, warnMsg){ //输入足够长 if(value.length < length) return warnMsg; }, isShortEnough: function(value, length, warnMsg){ //输入足够短 if(value.length > length) return warnMsg; }, isMobile: function(value, warnMsg){ //手机号验证 var reg = /^1[3|5|8][0-9]{9}$/; if(!reg.test(value)) return warnMsg; } } var Validator = function(){ //环境类 this.rules = []; //数组用于存放负责验证的函数 }; Validator.prototype.add = function(domNode, ruleArr){ //添加验证规则 var self = this; for(var i = 0, rule; rule = ruleArr[i++];){ (function(rule){ var strategyArr = rule.strategy.split(':'), warnMsg = rule.warnMsg; self.rules.push(function(){ var tempArr = strategyArr.concat(); var ruleName = tempArr.shift(); tempArr.unshift(domNode.value); tempArr.push(warnMsg); return vldStrategy[ruleName].apply(domNode, tempArr); }); })(rule); } return this; }; Validator.prototype.start = function(){ //开始验证表单 for(var i = 0, vldFn; vldFn = this.rules[i++];){ var warnMsg = vldFn(); if(warnMsg){ warn.textContent = warnMsg; return false; } } } var vld = new Validator(); vld.add(form.username, [ { strategy: 'isNonEmpty', warnMsg: '账号不能为空' }, { strategy: 'isLongEnough:4', warnMsg: '账号不能小于4位' }, { strategy: 'isShortEnough:20', warnMsg: '账号不能大于20位' } ]).add(form.password, [ { strategy: 'isNonEmpty', warnMsg: '密码不能为空' } ]).add(form.phonenum, [ { strategy: 'isNonEmpty', warnMsg: '手机号不能为空' }, { strategy: 'isMobile', warnMsg: '手机号格式不正确' } ]); var submitMsg = function(){ var msg = { username: form.username.value, password: form.password.value, phonenum: form.phonenum.value } //ajax('...', msg); return warn.textContent = '用户信息已成功提交至服务器'; } submitMsg = submitMsg.before(vld.start.bind(vld)); form.submit.onclick = function(){ submitMsg(); }; //这里只是模拟提交，实际应该用form.onsubmit
问题分析
总结一下易错的地方还有我敲得时候遇到的问题