Test migration to jest by hand

Apparently using regular expressions is way easier.

test/stringPermutations/stringPermutations.js

@@ -0,0 +1,11 @@
+const stringPermutations = str => {
+if (str.length <= 2) return str.length === 2 ? [str, str[1] + str[0]] : [str];
+return str
+.split('')
+.reduce(
+(acc, letter, i) =>
+acc.concat(stringPermutations(str.slice(0, i) + str.slice(i + 1)).map(val => letter + val)),
+[]
+);
+};
+module.exports = stringPermutations;