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Anagrams - JavaScript Algorithms

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    Curtis Warcup

Anagrams are words that contain the same letters, but in a different order. For example, the word "anagram" can be rearranged to make another word, "nag a ram".

Directions: Check to see if two provided strings are anagrams of each other.

One string is an anagram of another if it uses the same characters in the same quantity. Only consider characters, not spaces or punctuation. Consider capital letters to be the same as lower case.


  anagrams('rail safety', 'fairy tales') --> True
  anagrams('RAIL! SAFETY!', 'fairy tales') --> True
  anagrams('Hi there', 'Bye there') --> False

Tips for dealing with considering only characters, spaces and punctuation:

  • use regex to remove all non-alphanumeric characters. The /w character class matches any alphanumeric character. Equivalent to [^a-za-z0-9_]. For example, /\W/ or /[^a-za-z0-9_]/ matches "%" in "50%" and "É" in "Émanuel".
const word = 'HI there!!!'

let newWord = word.replace(/[^\w]/g, '').toLowerCase()

console.log(newWord) // hithere

We can compare the keys of an object to see if they are equal.

const obj = {
  a: 1,
  b: 1,
  c: 1,


Solution 1: Character Map

  • We can create a character map using an object to compare the two strings.
  • Count the number of keys in our object and compare it to the number of keys in the other object.
  • We can also compare length of both strings.


// helper function to create character map
function createCharMap(str) {
  let obj = {}

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

function anagram(str1, str2) {
  // create objects of each string using helper function
  const obj1 = createCharMap(str1)
  const obj2 = createCharMap(str2)

  // compare the number of keys in each object
  if (Object.keys(obj1).length !== Object.keys(obj2).length) {
    return false

  //compare characters in each object
  for (let char in obj1) {
    if (obj1[char] !== obj2[char]) {
      return false
  return true

console.log(anagrams('rail safety', 'fairy tales')) // true
console.log(anagrams('something else', 'fairy tales')) // false

Solution 2: Sort()

We can use the sort() method to sort the characters in a string and then compare the two strings.

Recall how the sort() method sorts an array.

const numbers = [10, 30, 5, -90]
console.log(numbers.sort()) // [-90, 5, 10, 30]


  1. Clean up both strings using regex to remove all non-alphanumeric characters.
  2. Use toLowerCase() to make both strings lowercase.
  3. Sort both strings using sort()
  4. If the two strings are identical, they are anagrams.
function anagrams(stringA, stringB) {
  return cleanString(stringA) === cleanString(stringB)

// helper function to clean up string
function cleanString(str) {
  return str.replace(/[^\w]/g, '').toLowerCase().split('').sort().join('')

console.log(anagrams('rail safety', 'fairy tales')) // true