gistfile1.txt

function Foo(val) {
    this.value = val;

    this.increment = function() {
        this.value++;
    }
}

var f = new Foo(11);
f.increment();
console.log(f.value);

function Bar(val) {
   this.value = val;
}

Bar.prototype.increment = function() {
    this.value++;
}

var b = new Bar(22);
b.increment();
console.log(b.value);