closures.js

function Counter(start) {
    var count = start;
    return {
        increment: function() {
            count++;
        },

        get: function() {
            return count;
        }
    }
}

var foo = Counter(4);
foo.increment();
foo.get(); // 5


//closures within a loop

for(var i = 0; i < 10; i++) {
    (function(e) {
        setTimeout(function() {
            console.log(e);  
        }, 1000);
    })(i);
}

//an alternative way
for(var i = 0; i < 10; i++) {
    setTimeout(console.log.bind(console, i), 1000);
}

// Contructors
function Foo(){
    this.bar  = 55;     // no explicit return
}

new Foo();      // 'this' will be returned

function Foo(){
    return 55;          // explicit return of a non-object
}

new Foo();          // new object will be returned

function Foo(){
    return {bar : 55}       // explicit return of an object
}

new Foo();          // {bar: 55} will be returned


//factories
function Person() {
    var obj = {};   
    obj.name = 'Gaurav';

    var age = 21;
    obj.setName = function(name) {
        this.name = name;
    }

    obj.getAge = function() {
        return age;
    }
    return obj;
}