[twiss]

To those curious what it does, Object.create(Array) creates an object with the Array constructor function (not the Array prototype) as its prototype. The Array constructor function, like all functions, has a length property indicating the number of arguments it takes. That property is accessed through the created object's prototype chain.

The Array constructor's length property is defined to be 1, referring to the fact that if you call it with 1 number, you get an array of that length filled with undefineds. If you call it with something else or another number of arguments, you get an array filled with the arguments.