`set-array` is a tiny JavaScript utility that lets you declaratively describe how to modify an array—updating, inserting, appending, prepending, merging or deleting items—using a plain‑object syntax where keys are indices (including negative, “*”, “-0” and “+” modifiers). It returns a new array (leaving the original untouched) and works in Node ≥ 18 and browsers, making it handy for configuration files, API patch payloads, or any situation where array manipulation needs to be expressed as data rather than imperative code.