# datavolve

> Tiny, type-safe evolutions for versioned data. Storage-agnostic and dependency-free.

- URL: https://evilmartians.com/opensource/datavolve
- GitHub: https://github.com/psd-coder/datavolve
- Website: https://datavolve.psdcoder.dev/
- Authors: Pavel Grinchenko

---

datavolve brings old persisted data up to the shape your code expects today. Give it a value that an older version of your app saved in localStorage, IndexedDB, or a JSON file, and it runs the value through a chain of forward-only evolutions, with full type inference at every step.

* **Typed chain.** Each evolution gets the type of the previous version's value. You don't write types for the middle steps.
* **Forward-only.** Every evolution is a pure `(prev) => next` function. There are no reverse migrations and no side effects.
* **Never throws.** `run` returns a result object, so the compiler makes you handle data that is newer than your build, a bad version number, or an evolution that failed.
* **Storage-agnostic.** You pass the stored version in as an argument. datavolve never reads or writes storage.
* **Tiny.** 258 B, zero dependencies, ESM only.

```ts
import { datavolve } from "datavolve"

const settings = datavolve()
  .add(1, (raw) => ({ theme: "light" }))
  .add(2, (v1) => ({ ...v1, fontScale: 1 }))
  .add(3, (v2) => ({ ...v2, theme: v2.theme === "light" ? "day" : "night" }))

const result = settings.run(storedValue, storedVersion)

if (result.success) {
  save({ version: result.version, value: result.value })
}
```

The full API and guides for checking untrusted input are at [datavolve.psdcoder.dev](https://datavolve.psdcoder.dev/).