JavaScript设计模式--策略模式

var strategies = {
    "S": function(salary) {
        return salary * 4;
    },
    "A": function(salary) {
        return salary * 3;
    },
    "B": function(salary) {
        return salary * 2;
    }
};

// 接收请求
var calculateBonus = function(level, salary) {
    return strategies[level](salary);
};

// 测试
console.log(calculateBonus("S", 20000));
console.log(calculateBonus("A", 20000));
console.log(calculateBonus("B", 20000));

/* 校验策略对象 */
var validateStrategies = {
    isEmpty: function (val, errorMsg) {
        if (!val) {
            return errorMsg;
        }
    },
    isURL: function (val, errorMsg) {
        if (!new RegExp("^(http:\\/\\/|https:\\/\\/)?([\\w\\-]+\\.)+[\\w\\-]+(\\/[\\w\\-\\.\\/?\\@\\%\\!\\&=\\+\\~\\:\\#\\;\\,]*)?$").test(val)) {
            return errorMsg;
        }
    },
    isEmail: function (val, errorMsg) {
        if (!new RegExp('\\w+((-\\w+)|(\\.\\w+))*\\@[A-Za-z0-9]+((\\.|-)[A-Za-z0-9]+)*\\.[A-Za-z0-9]+').test(val)) {
            return errorMsg;
        }
    },
    isMaxLength: function (val, length, errorMsg) {
        if (val.length > length) {
            return errorMsg;
        }
    },
    isMinLength: function (val, length, errorMsg) {
        if (val.length < length) {
            return errorMsg;
        }
    }
};

/* validator类 */
var validator = function () {
    // 缓存验证策略
    this.cache = [];
};

/**
 * 添加要验证的策略
 * @param dom       要验证的dom元素
 * @param rules     验证规则
 */
validator.prototype.add = function (dom, rules) {
    var self = this;
    for (var i = 0, rule; rule = rules[i++];) {
        (function (rule) {
            var strategyAry = rule.strategy.split(":");     // ["isMaxLength", "10"]
            var errorMsg = rule.errorMsg;                   // "内容长度不能超过10"
            self.cache.push(function () {
                var strategy = strategyAry.shift();         // "isMaxLength"
                strategyAry.unshift(dom.value);             // ["1@qq", "10"]
                strategyAry.push(errorMsg);                 // ["1@qq", "10", "内容长度不能超过10"]
                return validateStrategies[strategy].apply(dom, strategyAry);
            });
        })(rule);
    }
};

/* 开始校验 */
validator.prototype.start = function () {
    for (var i = 0, validateFunc; validateFunc = this.cache[i++];) {
        var errorMsg = validateFunc();
        if (errorMsg) {
            return errorMsg;
        }
    }
};


// 测试

<label for="email">邮箱：</label><input type="text" name="email" value="1@qq">

var validatorInstance = new validator();
validatorInstance.add(
    document.getElementsByName("email")[0], 
    [{
        strategy: "isEmpty",
        errorMsg: "内容不能为空"
    },{
        strategy: "isMaxLength:10",
        errorMsg: "内容长度不能超过10"
    },{
        strategy: "isEmail",
        errorMsg: "email格式不对"
    }]);
errorMsg = validatorInstance.start();