add data patterns js

Program's_Contributed_By_Contributors/JavaScript_Programs/Data Patterns/behaviourl/mediator.js

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+var Participant = function (name) {
+    this.name = name;
+    this.chatroom = null;
+};
+
+Participant.prototype = {
+    send: function (message, to) {
+        this.chatroom.send(message, this, to);
+    },
+    receive: function (message, from) {
+        console.log(from.name + " to " + this.name + ": " + message);
+    }
+};
+
+var Chatroom = function () {
+    var participants = {};
+
+    return {
+
+        register: function (participant) {
+            participants[participant.name] = participant;
+            participant.chatroom = this;
+        },
+
+        send: function (message, from, to) {
+            if (to) {                      // single message
+                to.receive(message, from);
+            } else {                       // broadcast message
+                for (key in participants) {
+                    if (participants[key] !== from) {
+                        participants[key].receive(message, from);
+                    }
+                }
+            }
+        }
+    };
+};
+
+function run() {
+
+    var yoko = new Participant("Yoko");
+    var john = new Participant("John");
+    var paul = new Participant("Paul");
+    var ringo = new Participant("Ringo");
+
+    var chatroom = new Chatroom();
+    chatroom.register(yoko);
+    chatroom.register(john);
+    chatroom.register(paul);
+    chatroom.register(ringo);
+
+    yoko.send("All you need is love.");
+    yoko.send("I love you John.");
+    john.send("Hey, no need to broadcast", yoko);
+    paul.send("Ha, I heard that!");
+    ringo.send("Paul, what do you think?", paul);
+}

Program's_Contributed_By_Contributors/JavaScript_Programs/Data Patterns/behaviourl/observer.js

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+function Click() {
+    this.handlers = [];  // observers
+}
+
+Click.prototype = {
+
+    subscribe: function (fn) {
+        this.handlers.push(fn);
+    },
+
+    unsubscribe: function (fn) {
+        this.handlers = this.handlers.filter(
+            function (item) {
+                if (item !== fn) {
+                    return item;
+                }
+            }
+        );
+    },
+
+    fire: function (o, thisObj) {
+        var scope = thisObj || window;
+        this.handlers.forEach(function (item) {
+            item.call(scope, o);
+        });
+    }
+}
+
+function run() {
+
+    var clickHandler = function (item) {
+        console.log("fired: " + item);
+    };
+
+    var click = new Click();
+
+    click.subscribe(clickHandler);
+    click.fire('event #1');
+    click.unsubscribe(clickHandler);
+    click.fire('event #2');
+    click.subscribe(clickHandler);
+    click.fire('event #3');
+}

Program's_Contributed_By_Contributors/JavaScript_Programs/Data Patterns/creational/builder.js

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+function Shop() {
+    this.construct = function (builder) {
+        builder.step1();
+        builder.step2();
+        return builder.get();
+    }
+}
+
+function CarBuilder() {
+    this.car = null;
+
+    this.step1 = function () {
+        this.car = new Car();
+    };
+
+    this.step2 = function () {
+        this.car.addParts();
+    };
+
+    this.get = function () {
+        return this.car;
+    };
+}
+
+function TruckBuilder() {
+    this.truck = null;
+
+    this.step1 = function () {
+        this.truck = new Truck();
+    };
+
+    this.step2 = function () {
+        this.truck.addParts();
+    };
+
+    this.get = function () {
+        return this.truck;
+    };
+}
+
+function Car() {
+    this.doors = 0;
+
+    this.addParts = function () {
+        this.doors = 4;
+    };
+
+    this.say = function () {
+        console.log("I am a " + this.doors + "-door car");
+    };
+}
+
+function Truck() {
+    this.doors = 0;
+
+    this.addParts = function () {
+        this.doors = 2;
+    };
+
+    this.say = function () {
+        console.log("I am a " + this.doors + "-door truck");
+    };
+}
+
+function run() {
+    var shop = new Shop();
+    var carBuilder = new CarBuilder();
+    var truckBuilder = new TruckBuilder();
+    var car = shop.construct(carBuilder);
+    var truck = shop.construct(truckBuilder);
+
+    car.say();
+    truck.say();
+}

Program's_Contributed_By_Contributors/JavaScript_Programs/Data Patterns/creational/factory.js

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+var Factory = function () {
+    this.createEmployee = function (type) {
+        var employee;
+
+        if (type === "fulltime") {
+            employee = new FullTime();
+        } else if (type === "parttime") {
+            employee = new PartTime();
+        } else if (type === "temporary") {
+            employee = new Temporary();
+        } else if (type === "contractor") {
+            employee = new Contractor();
+        }
+
+        employee.type = type;
+
+        employee.say = function () {
+            console.log(this.type + ": rate " + this.hourly + "/hour");
+        }
+
+        return employee;
+    }
+}
+
+var FullTime = function () {
+    this.hourly = "$12";
+};
+
+var PartTime = function () {
+    this.hourly = "$11";
+};
+
+var Temporary = function () {
+    this.hourly = "$10";
+};
+
+var Contractor = function () {
+    this.hourly = "$15";
+};
+
+function run() {
+
+    var employees = [];
+    var factory = new Factory();
+
+    employees.push(factory.createEmployee("fulltime"));
+    employees.push(factory.createEmployee("parttime"));
+    employees.push(factory.createEmployee("temporary"));
+    employees.push(factory.createEmployee("contractor"));
+
+    for (var i = 0, len = employees.length; i < len; i++) {
+        employees[i].say();
+    }
+}

Program's_Contributed_By_Contributors/JavaScript_Programs/Data Patterns/creational/prototype.js

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+function CustomerPrototype(proto) {
+    this.proto = proto;
+
+    this.clone = function () {
+        var customer = new Customer();
+
+        customer.first = proto.first;
+        customer.last = proto.last;
+        customer.status = proto.status;
+
+        return customer;
+    };
+}
+
+function Customer(first, last, status) {
+
+    this.first = first;
+    this.last = last;
+    this.status = status;
+
+    this.say = function () {
+        console.log("name: " + this.first + " " + this.last +
+            ", status: " + this.status);
+    };
+}
+
+function run() {
+
+    var proto = new Customer("n/a", "n/a", "pending");
+    var prototype = new CustomerPrototype(proto);
+
+    var customer = prototype.clone();
+    customer.say();
+}
+

Program's_Contributed_By_Contributors/JavaScript_Programs/Data Patterns/creational/singelton.js

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+var Singleton = (function () {
+    var instance;
+
+    function createInstance() {
+        var object = new Object("I am the instance");
+        return object;
+    }
+
+    return {
+        getInstance: function () {
+            if (!instance) {
+                instance = createInstance();
+            }
+            return instance;
+        }
+    };
+})();
+
+function run() {
+
+    var instance1 = Singleton.getInstance();
+    var instance2 = Singleton.getInstance();
+
+    console.log("Same instance? " + (instance1 === instance2));
+}

Program's_Contributed_By_Contributors/JavaScript_Programs/Data Patterns/structural/adapter.js

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+
+// old interface
+
+function Shipping() {
+    this.request = function (zipStart, zipEnd, weight) {
+        // ...
+        return "$49.75";
+    }
+}
+
+// new interface
+
+function AdvancedShipping() {
+    this.login = function (credentials) { /* ... */ };
+    this.setStart = function (start) { /* ... */ };
+    this.setDestination = function (destination) { /* ... */ };
+    this.calculate = function (weight) { return "$39.50"; };
+}
+
+// adapter interface
+
+function ShippingAdapter(credentials) {
+    var shipping = new AdvancedShipping();
+
+    shipping.login(credentials);
+
+    return {
+        request: function (zipStart, zipEnd, weight) {
+            shipping.setStart(zipStart);
+            shipping.setDestination(zipEnd);
+            return shipping.calculate(weight);
+        }
+    };
+}
+
+function run() {
+
+    var shipping = new Shipping();
+    var credentials = { token: "30a8-6ee1" };
+    var adapter = new ShippingAdapter(credentials);
+
+    // original shipping object and interface
+
+    var cost = shipping.request("78701", "10010", "2 lbs");
+    console.log("Old cost: " + cost);
+
+    // new shipping object with adapted interface
+
+    cost = adapter.request("78701", "10010", "2 lbs");
+
+    console.log("New cost: " + cost);
+}

Program's_Contributed_By_Contributors/JavaScript_Programs/Data Patterns/structural/facade.js

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+var Mortgage = function (name) {
+    this.name = name;
+}
+
+Mortgage.prototype = {
+
+    applyFor: function (amount) {
+        // access multiple subsystems...
+        var result = "approved";
+        if (!new Bank().verify(this.name, amount)) {
+            result = "denied";
+        } else if (!new Credit().get(this.name)) {
+            result = "denied";
+        } else if (!new Background().check(this.name)) {
+            result = "denied";
+        }
+        return this.name + " has been " + result +
+            " for a " + amount + " mortgage";
+    }
+}
+
+var Bank = function () {
+    this.verify = function (name, amount) {
+        // complex logic ...
+        return true;
+    }
+}
+
+var Credit = function () {
+    this.get = function (name) {
+        // complex logic ...
+        return true;
+    }
+}
+
+var Background = function () {
+    this.check = function (name) {
+        // complex logic ...
+        return true;
+    }
+}
+
+function run() {
+    var mortgage = new Mortgage("Joan Templeton");
+    var result = mortgage.applyFor("$100,000");
+
+    console.log(result);
+}