Group Anagrams

groupAnagrams.js

function groupAnagrams(listOfStrings) {
  return listOfStrings.reduce((groups, string) => {
    for (let i = 0; i < groups.length; i++) {
      if (isAnagram(groups[i][0], string)) {
        groups[i].push(string);
        return groups;
      }
    }
    groups.push([string]);
    return groups;
  }, []);
}

function isAnagram(firstString, secondString) {
  const firstCharacters = firstString.split('');
  const secondCharacters = secondString.split('');
  for (let i = 0; i < secondCharacters.length; i++) {
    const characterIndex = firstCharacters.indexOf(secondCharacters[i]);
    if (characterIndex === -1) return false;
    firstCharacters.splice(characterIndex, 1);
  }
  if (firstCharacters.length) return false;
  return true;
}

console.log(groupAnagrams(['catt', 'cat', 'bat', 'cinema', 'tab', 'tac', 'iceman', 'act']));