Helper functions...

[njsfield]

function validateInput(query) {
  return query.replace(/[^a-z]/gi, '');
}

function makeRegExp(input) {
  return new RegExp('^' + input, 'i');
}

function match(list, regex) {
  return list.filter(function(word) { return regex.test(word); });
}

These are great! :) We used methods like these throughout our project but didn't think to wrap them in functions, nice :)
Perhaps put these into a 'helpers.js' file and require it in to files that need it?