Object mapping and filtering

object-map-filter.js

var MapObj = function(obj, mapFn) {
  var key, result, val;
  if (obj.length && obj.join) {
    return obj.map(mapFn);
  }
  result = {};
  for (key in obj) {
    val = obj[key];
    result[key] = mapFn(val, key);
  }
  return result;
};

var FilterObj = function(obj, filterFn) {
  var key, result, val;
  if (obj.length && obj.join) {
    return obj.filter(filterFn);
  }
  result = {};
  for (key in obj) {
    val = obj[key];
    if (filterFn(val, key)) {
      result[key] = val;
    }
  }
  return result;
};