Creates a reverse map in Javascript - source: http://stackoverflow.com/questions/10974493/javascript-quickly-lookup-value-in-object-like-we-can-with-properties

reversemap.js

var map = {
      "s":"d", "m":"e",
      "e":"h", "x":"l",
      "z":"o", "i":"r",
      "a":"w", "o":"!",
      "-":" "
    },
    reverseMap = {}

for (j in map){
  if (!Object.prototype.hasOwnProperty.call(map, j)) continue
  reverseMap[map[j]] = j
}