CallApply.js

// Invoking a function and applying it have the same
// result. apply() takes two parameters: the first one is an object to bind to this inside of
// the function, the second is an array or arguments, which then becomes the array-like
// arguments object available inside the function. If the first parameter is null, then this
// points to the global object, which is exactly what happens when you call a function
// that is not a method of a specific object.

// When a function is a method of an object, there’s no null reference passed around. Here the 
// object becomes the first argument to apply():

// In addition to apply(), there’s a call() method of the Function.prototype
// object, but it’s still just syntax sugar on top of apply(). Sometimes it’s better to use the
// sugar: When you have a function that takes only one parameter, you can save the work
// of creating arrays with just one element:

// the second is more efficient, saves an array
sayHi.apply(alien, ["humans"]); // "Hello, humans!"
sayHi.call(alien, "humans"); // "Hello, humans!"