Patterns for Enforcing new

by shwon24

HTML

<link rel="stylesheet" href="http://twitter.github.io/bootstrap/assets/css/bootstrap.css">
<div ng-controller='MyCtrl'>
    <h4>Patterns for Enforcing new</h4>
    <ul>
        <li ng-repeat='log in logs'>{{log}}</li>
    </ul>
</div>

JavaScript

var app = angular.module('myapp', []);

// Patterns for Enforcing new
app.controller('MyCtrl', function($scope) {
    $scope.logs = [];
    function log() {
        $scope.logs.push(Array.prototype.slice.call(arguments).join(''));
    }
    // constructor 
    function Waffle() {
        this.tastes = "yummy";
    }
    // a new object
    var good_morning = new Waffle();
    log('type of good_morning=', typeof good_morning); // object
    log('good_morning.tastes=', good_morning.tastes); // yummy
    
    // antipattern: forgotten `new`
    var not_good_morning = Waffle();
    log("typeof not_good_morning=", typeof not_good_morning); // undefined
    log('window.tastes=', window.tastes); // "yummy"
    
    // that을 반환하면 된다.
    function ThatWaffle() {
        // var that = {};
        // that.tastes = "gooood";
        // return that;
        return {
            tastes: "gooood"
        };
    }
    
    var that1 = new ThatWaffle();
    var that2 = ThatWaffle();
    log('that1.tastes=', that1.tastes);
    log('that2.tastes=', that2.tastes);
    
    // 하지만 생성자 프로토타입을 쓸모 없어졌다. ThatWaffle 프로토타입에 추가한 멤버는 사용할 수 없다.
    
    // Self-Invoking Constructor
    function SelfInvokeWaffle() {
        if (!(this instanceof SelfInvokeWaffle)) {
            return new SelfInvokeWaffle();
        }
        this.tastes = "awesome";
    }
    SelfInvokeWaffle.prototype.wantAnother = true;
    
    var first = new SelfInvokeWaffle();
    var second = SelfInvokeWaffle();
    log('first.tastes=', first.tastes);  //  awesome
    log('second.tastes=', first.tastes); //  awesome
    log('first.wantAnother=', first.wantAnother);  //  true
    log('second.wantAnother=', first.wantAnother); //  true
});