Quick example of composing objects (and functions in Javascript)

composition.js

function worker(x) {
    console.log("Look at me I'm calling some function");
    if('someFunction' in x) {
        x.someFunction();
    }
    else{
        console.log("Wait... there's nothing here");
    }
};

var someObject = {};

worker(someObject);

someObject.someFunction = function(){
    console.log("I'm Mr Meeseks!");
}

worker(someObject);