Prefer maps to objects for dynamic data

Objects aren’t ideal for manipulation, especially in Typescript. If you add a key, the typings get thrown of. Prefer a JS Map.

MDN Link

Checking if items is in list

new Set(arr).has(item) is actually much faster than Array.includes() for checking the existence of primitives in a set. Prefer that.

MDM Link

If you need a function for lookup, use Array.some()

Delete single item from list

Just as above. Array.from(new Set(arr).delete(key)) is faster than removing it with filter. Also works only on primitives.