concat() does not mutate the array, it creates a new one. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/concat https:/

concat() does not mutate the array, it creates a new one. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/concat https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...