Solve Anagrams

anagram.js

// beautiful
function findAnagram(parent, child) {
  // split the parent string into chars and iterate
  return parent.split('').map(function (char, index, arr) {
    // map each char in parent to an array of substrings with the same length as child.length
    // and alphabetize the substrings for easy comparison later
    return arr.slice(index, index + child.length).sort().join('');
  }).filter(function (subset) {
    // compare the alphabetized substring to the alphabetized child
    return subset === child.split('').sort().join('');
  }).length;
}

// fast
function findAnagram(parent, child) {
  var all = [],
      matches = 0,
      len = child.length,
      test,
      i, j, k;

  for (i = 0; i <= parent.length - len; i++) {
    all.push(parent.substr(i, len));
  }

  // find matches
  for (i = 0; i < all.length; i++) {
    test = child;
    for (j = 0; j < len; j++) {
      for (k = test.length - 1; k >=0; k--) {
        if (all[i].charAt(j) === test.charAt(k)) {
          test = test.slice(0, k) + test.slice(k + 1);
          break;
        }
      }
    }
    if (test.length === 0) { matches++ }
  }
  return matches;
}

findAnagram('AdnBndAndBdaBn', 'dAn') // 4 ("Adn", "ndA", "dAn", "And")
findAnagram('AbrAcadAbRa', 'cAda') // 2