The **split-string-or-buffer-once-pmb** package provides a tiny utility that mimics `String.split` but only splits at the first (or last) occurrence of a separator, and it works equally on JavaScript strings, Buffers, or any object supporting `indexOf`/`lastIndexOf` and `slice`. It exports a `splitOnce` function (with optional `last` mode) that returns the two parts as an array or `false` if the separator isn’t found, making it useful for developers who need a simple, generic “split‑once” operation without pulling in larger libraries.