Single or Many

Sometimes a function should accept either a single item or an array of items. Use Array.isArray to decide which one you have and normalize to one consistent shape.

function ensureArray(s: string | string[]) {
  return Array.isArray(s) ? s : [s];
}

Return a new array every time so callers can safely reuse the result.

Your Task

Normalize input into an array of strings.

Write function asList(v: string | string[]): string[].
If v is a string, return [v].
If v is an array, return a new array with the same elements (do not return the input reference).
Do not mutate the input.