`left-split` is a tiny Node.js utility that modifies JavaScript’s `String.prototype.split` behavior when a capturing group is used. Instead of returning the separator as a separate array element, it appends the separator to the preceding token, yielding a more natural “left‑hand” split. It’s useful for developers who need cleaner tokenization of strings (e.g., preserving whitespace or line‑break characters with the preceding text) without manual post‑processing.