My favourite, essential " polyfills " for projects with coffeescripts.

polyfills.coffee

# xxx turn this into a bower/npm module
Object.defineProperty Array.prototype, "last", { get: -> this[this.length - 1]}
Object.defineProperty Array.prototype, "first", { get: -> this[0]}
Function::property = (prop, desc) ->
  Object.defineProperty @prototype, prop, desc
Function::getter = (prop, get) ->
  Object.defineProperty @prototype, prop, {get, configurable: yes}
Function::setter = (prop, set) ->
  Object.defineProperty @prototype, prop, {set, configurable: yes}