generics.js

var foo = {
    a: 1
};

var bar = {
    a: 2,
    b: "bar"
};

function X() {
    console.log("a is " + this.a);
}

function Y() {
    console.log("a is " + this.a);
    console.log("b is " + this.b);
}

X.call(foo); // a is 1

X.call(bar); // a is 2
Y.call(bar); // a is 2 \n b is bar