Words that contain a part

Write a function filterWords(words, part) that returns the words from the array words that contain part as a substring. For ['ant', 'tiger', 'elephant'] and 'ant' the answer is ['ant', 'elephant'].

• words is an array of words (it can be empty). part is a non-empty string of letters.
• The search is case insensitive: with 'ant' the words 'Antelope' and 'PLANT' match too, and 'ANT' as part finds 'plant'.
• part can be anywhere in the word: at the start, in the middle or at the end.
• Keep the words in their order and with their own spelling. If a word is in the list twice, it is in the answer twice.
• If nothing matches, return an empty array.
• Return a new array. Do not change words.

includes and filter do most of the work.