---
title: JavaScript SDK 4.0.0
summary: null
url: >-
  https://www.fastly.com/documentation/reference/changes/2026/10/javascript-sdk-4.0.0
---

## Changed

- this enables AOT compilation by default, which might be unexpected, but will make our default operation much faster.

## Added

- Allow URIs longer than 8192 bytes ([#1585](https://github.com/fastly/js-compute-runtime/issues/1585)) ([6ac66df](https://github.com/fastly/js-compute-runtime/commit/6ac66dff1aff48a9f271251b1d3a8a052329471e))
- enable AOT by default ([#1598](https://github.com/fastly/js-compute-runtime/issues/1598)) ([dfcc17f](https://github.com/fastly/js-compute-runtime/commit/dfcc17f31822f8a6eac7a28b52e7c93eb45aa33e))

## Fixed

- change zip extractor for wasmtime package ([5a8886e](https://github.com/fastly/js-compute-runtime/commit/5a8886ed12b8159bd21b1ba054ccb9768924047f))
- Ensure additions to headers in beforeSend are applied ([#1600](https://github.com/fastly/js-compute-runtime/issues/1600)) ([1ae9e5b](https://github.com/fastly/js-compute-runtime/commit/1ae9e5b36193d3cb16865ba7c6b918d740cddcee))
- get documentation generation working again ([#1595](https://github.com/fastly/js-compute-runtime/issues/1595)) ([9e3f16b](https://github.com/fastly/js-compute-runtime/commit/9e3f16bb10bba95d4c34715079f558ed10215f52))
- handle potential NULL pointer dereference in debug logging ([#1593](https://github.com/fastly/js-compute-runtime/issues/1593)) ([1e5eb8b](https://github.com/fastly/js-compute-runtime/commit/1e5eb8b8d920fd2a92dd0cdfeff846ccf32e4501))
- npm audit fix ([47ca0dc](https://github.com/fastly/js-compute-runtime/commit/47ca0dcc64a2faa21bd2cdb6fcefc80c1387fa06))
- reset pending unhandled promise rejection between requests ([#1596](https://github.com/fastly/js-compute-runtime/issues/1596)) ([f7d6c75](https://github.com/fastly/js-compute-runtime/commit/f7d6c756dda485ebac1e7f3f8492c0dd939b004e))
- Reset StarlingMonkey timers between requests ([#1597](https://github.com/fastly/js-compute-runtime/issues/1597)) ([2b35d6f](https://github.com/fastly/js-compute-runtime/commit/2b35d6f2acb6f6e4460117ba4c0b1d1b471e18ad))