isAnagram.js

const assert = require('assert')


/* takes in two strings, and returns if they are anagrams */
function isAnagram(a,b) {
  if (a.length != b.length) {
    return false
  }
  var o1 = {}
  var o2 = {}
  var i
  /* TODO: how could you refactor these two loops? */
  for (i = 0; i < a.length; i++) {
    var ch = a[i]
    if (ch in o1) {
      o1[ch] += 1
    } else {
      o1[ch] = 1
    }
  }
  for (i = 0; i < b.length; i++) {
    var ch = b[i]
    if (ch in o2) {
      o2[ch] += 1
    } else {
      o2[ch] = 1
    }
  }
  /* TODO: why do we only need to iterate over o1 and not o2 as well */
  for (var k in o1) {
    if (o1[k] != o2[k]) {
      return false
    }
  }
  return true
}

/* test */
assert(isAnagram('aba', 'aab') === true)
assert(isAnagram('aa', 'aab') === false)