Kata

Write

function findSubstring (s, words) {}

that given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring in s that is a concatenation of each word in words exactly once and without any intervening characters.

For example:

findSubstring("barfoofoobarthefoobarman", ["bar", "foo", "the"]) === [6, 9, 12]
findSubstring("helloworld", ["world", "hello"]) === [0]
findSubstring("helloworld", ["bar", "foo"]) === []