从表单校验看JavaScript策略模式的使用详解

<form action="xxx" id="registerForm">
	请输入用户名<input type="text" name="userName" id="name" />
	请输入密码<input type="text" name="password" id="pass" />
	请输入手机号<input type="text" name="phoneNumber" id="phone" />
	<button>提交</button>
</form>

<script>
	var registerForm=document.getElementById('registerForm')
	registerForm.onsubmit=function(){
		if(registerForm.userName.value==''){
			document.getElementById("name").setCustomValidity('用户名不能为空');
			return false;
		}
		if(registerForm.password.value.length<6){
			document.getElementById("pass").setCustomValidity('密码长度不能少于6位');
			return false;
		}
		if(!/(^1[3|5|8][0-9]{9}$)/.test(registerForm.phoneNumber.value)){
			document.getElementById("phone").setCustomValidity('手机号码格式不正确');
			return false;
		}
	}
</script>

var strategies={
	isNoneEmpty:function(value,errorMsg){
		if(value===''){
			return errorMsg;
		}
	},
	minLength:function(value,length,errorMsg){
		if(value.length<length){
			return errorMsg;
		}
	},
	isMobile:function(value,errorMsg){
		if(!/(^1[3|5|8][0-9]{9}$)/.test(value)){
			return errorMsg;
		}
	}
};

var Validator=function(){
	this.cache=[]; //用于保存接收到的校验规则
};
Validator.prototype.add=function(dom,rule,errorMsg){
	var ary=rule.split(':');
	this.cache.push(function(){
		var strategy=ary.shift();
		ary.unshift(dom.value);
		ary.push(errorMsg);
		return strategies[strategy].apply(dom,ary); //调用strategies对象的指定方法对象，并规定在函数对象内部this指向dom元素，ary作为参数传入
	});
};
Validator.prototype.start=function(){
	for(var i=0,validatorFunc;validatorFunc=this.cache[i++];){
		var msg=validatorFunc();
		if(msg){
			return msg;
		}
	}
}

var validataFunc=function(){
	var validator=new Validator();
	
	//添加校验规则
	validator.add(registerForm.userName,'isNoneEmpty','用户名不能为空');
	validator.add(registerForm.password,'minLength:6','密码长度不能少于6位');
	validator.add(registerForm.phoneNumber,'isMobile','手机号码格式不正确');
	
	var errMsg=validator.start(); //获得校验结果
	return errorMsg; //返回
}

var registerForm=document.getElementById('registerForm')
registerForm.onsubmit=function(){
	var errorMsg=validataFunc();
	if(errorMsg){
		//触发错误提示
		return false; //并阻止表单提交
	}
}

validator.add(registerForm.userName,'minLength:2','用户名不能少于2位')

validator.add(registerForm.userName,[{
	strategy:'isNoneEmpty',
	errorMsg:'用户名不能为空'
},{
	strategy:'minLength:2',
	errorMsg:'用户名长度不能少于2位'
}])

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);
				return strategies[strategy].apply(dom,strategyAry);
			});
		})(rule)
	}
}