index.js

let storage = [];
let tmpObject = {};

module.exports = {

  refresh: function (functionNames, modificationDates) {
    for (let i = 0; i < functionNames.length; i++) {
      tmpObject[functionNames[i]] = modificationDates[i];
    }

    functionNames.sort(
      (a, b) => {
        if (tmpObject[a] > tmpObject[b]) return 1;
        if (tmpObject[a] < tmpObject[b]) return -1;

        if (a > b) return 1;
        if (a < b) return -1;

        return 0;
      }
    );
    storage = functionNames;
  },

  guess: function (start) {
    function matchString(element, index, array) {
      return element.substring(0, start.length) === start;
    }

    if (!storage.some(matchString)) {
      return [];
    }

    let startIndex = 0;
    let counter = 0, i = startIndex;
    let result = [];
    let el;


    while(counter < 12 && i < storage.length) {
      el = storage[i];

      if (el.substring(0, start.length) === start) {
        result.push(el);
        counter++;
      }

      i++;
    }

    return result;
  }
}