JavaScript策略模式：重构表单校验逻辑

<html>
<head>
  <title>策略模式-校验表单</title>
  <meta content="text/html; charset=utf-8" http-equiv="Content-Type">
</head>
<body>
  <form id = "registerForm" method="post" action="http://xxxx.com/api/register">
    用户名：<input type="text" name="userName">
    密码：<input type="text" name="password">
    手机号码：<input type="text" name="phoneNumber">
    <button type="submit">提交</button>
  </form>
  <script type="text/javascript">
    var registerForm = document.getElementById('registerForm');
    registerForm.onsubmit = function() {
      if (registerForm.userName.value === '') {
        alert('用户名不可为空');
        return false;
      }
      if (registerForm.userName.value === '') {
        alert('用户名不可为空');
        return false;
      } 
      if (registerForm.userName.value.trim() === '') {
        alert('用户名不允许以空白字符命名');
        return false;
      } 
      if (registerForm.userName.value.trim().length < 2) {
        alert('用户名用户名长度不能小于2位');
        return false;
      } 
      if (registerForm.password.value.trim().length < 6) {
        alert('密码长度不能小于6位');
        return false;
      }
      if (!/^(13[0-9]|14[5|7]|15[0|1|2|3|5|6|7|8|9]|17[7]|18[0|1|2|3|5|6|7|8|9])\d{8}$/.test(registerForm.phoneNumber.value)) {
        alert('请输入正确的手机号码格式');
        return errorMsg;
       } 
    }
  </script>
</body>
</html>

<html>
<head>
  <title>策略模式-校验表单</title>
  <meta content="text/html; charset=utf-8" http-equiv="Content-Type">
</head>
<body>
  <form id = "registerForm" method="post" action="http://xxxx.com/api/register">
    用户名：<input type="text" name="userName">
    密码：<input type="text" name="password">
    手机号码：<input type="text" name="phoneNumber">
    <button type="submit">提交</button>
  </form>
  <script type="text/javascript">
    // 策略对象
    var strategies = {
      isNoEmpty: function (value, errorMsg) {
        if (value === '') {
          return errorMsg;
        }
      },
      isNoSpace: function (value, errorMsg) {
        if (value.trim() === '') {
          return errorMsg;
        }
      },
      minLength: function (value, length, errorMsg) {
        if (value.trim().length < length) {
          return errorMsg;
        }
      },
      maxLength: function (value, length, errorMsg) {
        if (value.length > length) {
          return errorMsg;
        }
      },
      isMobile: function (value, errorMsg) {
        if (!/^(13[0-9]|14[5|7]|15[0|1|2|3|5|6|7|8|9]|17[7]|18[0|1|2|3|5|6|7|8|9])\d{8}$/.test(value)) {
          return errorMsg;
        }        
      }
    }

    // 验证类
    var Validator = function() {
      this.cache = [];
    }
    Validator.prototype.add = function(dom, rules) {
      var self = this;
      for(var i = 0, rule; rule = rules[i++];) {
        (function(rule) {
          var strategyAry = rule.strategy.split(':');
          var errorMsg = rule.errorMsg;
          self.cache.push(function() {
          var strategy = strategyAry.shift();
          strategyAry.unshift(dom.value);
          strategyAry.push(errorMsg);
          return strategies[strategy].apply(dom, strategyAry);
          })
        })(rule)
      }
    };
    Validator.prototype.start = function() {
      for(var i = 0, validatorFunc; validatorFunc = this.cache[i++];) {
        var errorMsg = validatorFunc();
        if (errorMsg) {
          return errorMsg;
        }
      }
    };

    // 调用代码
    var registerForm = document.getElementById('registerForm');

    var validataFunc = function() {
      var validator = new Validator();
      validator.add(registerForm.userName, [{
        strategy: 'isNoEmpty',
        errorMsg: '用户名不可为空'
      }, {
        strategy: 'isNoSpace',
        errorMsg: '不允许以空白字符命名'
      }, {
        strategy: 'minLength:2',
        errorMsg: '用户名长度不能小于2位'
      }]);
      validator.add(registerForm.password, [ {
        strategy: 'minLength:6',
        errorMsg: '密码长度不能小于6位'
      }]);
      validator.add(registerForm.phoneNumber, [{
        strategy: 'isMobile',
        errorMsg: '请输入正确的手机号码格式'
      }]);
      var errorMsg = validator.start();
      return errorMsg;
    }

    registerForm.onsubmit = function() {
      var errorMsg = validataFunc();
      if (errorMsg) {
        alert(errorMsg);
        return false;
      }
    }
  </script>
</body>
</html>