Anagram difference

anagram-difference/index.js

@@ -0,0 +1,12 @@
+// https://www.codewars.com/kata/anagram-difference
+
+function anagramDifference([...a1], [...a2]) {
+  return a1.length + a2.length - intersection(a1, a2).length * 2;
+}
+
+// https://gist.github.com/gkucmierz/8ee04544fa842411f7553ef66ac2fcf0
+const intersection = (a1, a2) => {
+  const cnt = new Map();
+  a2.map(el => cnt[el] = el in cnt ? cnt[el] + 1 : 1);
+  return a1.filter(el => el in cnt && 0 < cnt[el]--);
+};