Function key_

recipes/JavaScript/579002_BaderOffer_Method/recipe-579002.js:205–211

(f)

//HELPERS

function key_(f) {
  if (typeof f == 'string')
     return function(p) { return p[f]; };
  if (typeof f == 'undefined')
    return function(x) { return x; };
  return f;
}

Array.prototype.max = function(key) {
  key = key_(key);