Here is a contrived example with respect to better understanding "best practices" in JavaScript. For example, I want to introduce a new method to the Array prototype that will return last element.

[1,2,3].last() // 3

But extending the basic Prototype is considered bad practice (except in the case of polyfills):

Array.prototype.last = function(){
  return this[this.length - 1];
}

How can I achieve this without it being "bad practice"?