anagramTest.js

// Do two given strings form an anagram?
// Possible solution should not be a higher Big O notation than O(n).
// Evaluation is case insensitive.

/**
 * @param str1 | String
 * @param str2 | String
 * @return Boolean
 */
const isItAnAnagram = (str1, str2) => {
  // type check arguments passed
  if (typeof str1 !== 'string' || typeof str2 !== 'string') {
    return false
  }
  
  // Normalize strings by lower casing them, and by removing any spaces
  const stringOne = str1.toLowerCase().replace(/\s/g, '')
  const stringTwo = str2.toLowerCase().replace(/\s/g, '')
  
  // check first if the two strings are of same length. If not return false and stop further execution.
  if (stringOne.length !== stringTwo.length) {
    return false
  }
  
  // Also check if the strings are identical. If yes, the second string is not considered an anagram.
  if (stringOne === stringTwo) {
    return false
  }
  
  // create an object for each string.
  let stringObject1 = {}
  let stringObject2 = {}
  
  // loop through each char adding it as a property to the object if it
  // is not yet present and assign the value of 1. 
  // Othwerwise if the char already exists as a property add 1 count. 
  for (let char of stringOne) {
    stringObject1[char] = stringObject1[char] + 1 || 1
  }
  
  for (let char of stringTwo) {
    stringObject2[char] = stringObject2[char] + 1 || 1
  }

  // iterate over first object and check for a corresponding char
  // in the seocnd object. If one found, check for equal count value.
  for (let char in stringObject1) {
    // If no match return false. 
    if (!stringObject2.hasOwnProperty(char)) {
      return false
    }
    
    // If no match return false. 
    if (stringObject1[char] !== stringObject2[char]) {
      return false
    }
    
   // Second string argument is an anagram of the first string argument.
    return true
  }
}