Javascript Interview Question: Anagram

anagram.js

/*
  Check to see if two strings are anagrams, where both strings have the same characters in the same quantity.
  Only consider characters, not spaces and punctuation. Consider the strings as case insensitive, where capital 
  letters are the same as lowercase letters.
*/

function anagram(str1, str2) {
  //Step 1: Create a data store for each string.
  const charMap1 = getCharMap(str1);
  const charMap2 = getCharMap(str2);
  const keysArr1 = Object.keys(charMap1);
  const keysArr2 = Object.keys(charMap2);
  
  //If the key arrays have different lengths, this is not an anagram.
  if (keysArr1.length !== keysArr2.length) {
    return false;
  }
  
  /*
    At this point, there are the same number of characters in each string.
    Are they an anagram? We'll use Array.every() helper to determine 
    if these two strings are anagrams. Thanks to the Array.every() helper,
    we can immediately return false if any callback returns false.
  */
  return keysArr1.every((char) => charMap1[char] === charMap2[char]);
}

function getCharMap(str) {
  let ds = {};
  
  for (let char of str.replace(/[^\w]/g, '').toLowerCase()) {
    ds[char] = ds[char] + 1 || 1;
  }
  
  return ds;
}

console.log(anagram('aba', 'aab')); //true
console.log(anagram('aba', 'abc')); //false
console.log(anagram('aba', 'abcd')); //false