JS 设计模式 #tags: 设计模式

jspattern.js

// 策略模式
var validator = {

    types: {},

    messages: [],

    config: {},

    validate: function (data) {

        var i, msg, type, checker, result_ok;

        this.messages = [];
        for (i in data) {

            if (data.hasOwnProperty(i)) {

                type = this.config[i];
                checker = this.types[type];

                if (!type) {
                    continue; // no need to validate
                }
                if (!checker) { // uh-oh
                    throw {
                        name: "ValidationError",
                        message: "No handler to validate type " + type
                    };
                }

                result_ok = checker.validate(data[i]);
                if (!result_ok) {
                    msg = "Invalid value for *" + i + "*, " + checker.instructions;
                    this.messages.push(msg);
                }
            }
        }
        return this.hasErrors();
    },

    // helper
    hasErrors: function () {
        return this.messages.length !== 0;
    }
};

validator.config = {
    first_name: 'isNonEmpty',
    age: 'isNumber',
    username: 'isAlphaNum'
};

// checks for non-empty values
validator.types.isNonEmpty = {
    validate: function (value) {
        return value !== "";
    },
    instructions: "the value cannot be empty"
};

// checks if a value is a number
validator.types.isNumber = {
    validate: function (value) {
        return !isNaN(value);
    },
    instructions: "the value can only be a valid number, e.g. 1, 3.14 or 2010"
};

// checks if the value contains only letters and numbers
validator.types.isAlphaNum = {
    validate: function (value) {
        return !/[^a-z0-9]/i.test(value);
    },
    instructions: "the value can only contain characters and numbers, no special symbols"
};

// 工厂模式 自然工厂
function CarMaker() {
    CarMaker.prototype.drive = function(){
        return "Vroom, Ihave" + this.doors + "doors";
    }
}
CarMaker.factory = function (type) {
    var constr = type, 
        newcar;
    if (typeof CarMaker[constr] !== "function") {
        throw {
            name: "Error",
            message: constr + "doesn't exist "
        };
    }
    if (typeof CarMaker[constr].prototype.drive !== "function") {
        CarMaker[constr].prototype = new CarMaker();
    }
    newcar = new CarMaker[constr]();
    return newcar;
};
CarMaker.Compact = function() {
    this.doors = 4;
}
// 内置对象工厂
var o = new Object()

o.constructor === Object;