Array.prototype.find and Array.prototype.findIndex quick and dirty polyfill

gistfile1.js

// WebReflection quick and dirty polyfill
(function(AP){
if ('find' in AP) return;
// quick size/safe version
// if predicate is not a function, call will throw
// if this is not array like, throws or nothing happens
function find(value) {
  return function (predicate, thisArg) {
    for(var
      k = 0,
      len = this.length;
      k < len && !(
        k in this &&
        predicate.call(thisArg, this[k], k, this)
      );
      k++
    );
    return value ? this[k] : k === len ? -1 : k;
  };
}
//https://gist.github.com/rwldrn/5079436
AP.find = find(!0);
// https://gist.github.com/rwldrn/5079427
AP.findIndex = find(!1);
}(Array.prototype));