Sort items by two digit outlines

SortByOutline

const faq = [
  {
    outline: "3.2",
    question: "Hello John?",
    answer: "Yes!"
  },
  {
    outline: "1.1",
    question: "Hello Julia?",
    answer: "Hi!"
  }
];

// Sort and group FAQ data
    faq.getSortKey = outline => {
      const leadingZero = numStr => `${numStr.length < 2 ? '0' : ''}${numStr}`;
      const numbers = outline.split('.');
      let ret = '';
      for (let i = 0; i < numbers.length; i++) {
        ret = `${ret}${leadingZero(numbers[i])}`;
      }
      return ret;
    };
    faq.sortedOutlines = faq.sort((itemA, itemB) => {
      const firstOne = faq.getSortKey(itemA.outline);
      const sortedPair = [firstOne, faq.getSortKey(itemB.outline)].sort();
      return firstOne === sortedPair[0] ? -1 : 1;
    });