This is the same as the last one, just done a little differently.

String.prototype.toSmallCaps.js

String.prototype.toSmallCaps = (function () {
  var letters = "abcdefghijklmnopqrstuvwxyz";
  var caps = "ᴀʙᴄᴅᴇғɢʜɪᴊᴋʟᴍɴᴏᴘǫʀsᴛᴜᴠᴡxʏᴢ";

  function translate(character) {
    var index = letters.indexOf(character);
    return index !== -1 ? caps.charAt(index) : character;
  }

  function mapReduce(value, transform) {
    var newValue = '';

    for (i = 0; i < value.length; i++) {
      newValue += transform(value[i]);
    }

    return newValue;
  }

  return function toSmallCaps() {
    return mapReduce(this, translate);
  };
}());