Function to detect 2 anagrams - Frequency counter method

Anagram.js

function validAnagram(strA, strB){
  if (strA.length !== strB.length) return false;
  const strAcounter = {};
  for (const char of strA) {
      strAcounter[char] = (strAcounter[char] || 0) + 1;
  }
  const strBcounter = {};
  for (const char of strB) {
      strBcounter[char] = (strBcounter[char] || 0) + 1;
  }
  const counter = Object.keys(strAcounter);
  for (const key of counter) {
      if (key in strBcounter) {
          if (strAcounter[key] !== strBcounter[key]) {
              return false;
          }
      } else {
          return false;
      }
  }
  return true;
}