__lookup?etter__ in ES5

lookup_etter.co

function lookup obj, key
  if obj?
    obj = Object obj
    do
      return that if Object.getOwnPropertyDescriptor(obj, key)?[@]
    while obj = Object.getPrototypeOf obj
  void

<[G S]>forEach -> Object"lookup#{it}etter" = lookup.bind it.toLowerCase() + \et

lookup_etter.js

(function(){
  function lookup(obj, key){
    var that, _ref;
    if (obj != null) {
      obj = Object(obj);
      do {
        if (that = (_ref = Object.getOwnPropertyDescriptor(obj, key)) != null ? _ref[this] : void 8) {
          return that;
        }
      } while (obj = Object.getPrototypeOf(obj));
    }
  }
  ['G', 'S'].forEach(function(it){
    return Object["lookup" + it + "etter"] = lookup.bind(it.toLowerCase() + 'et');
  });
}).call(this);

test.co

require \./lookup_etter
{strictEqual: eq} = require \assert

get = ->
set = ->
obj = Object.create null, p: {get, set}

eq get, Object.lookupGetter obj, \p
eq set, Object.lookupSetter obj, \p

eq get, Object.lookupGetter obj{} \p
eq set, Object.lookupSetter obj{} \p

eq void Object.lookupGetter {} \p
eq void Object.lookupGetter 42 \p