--- title: Bun v0.7.0 description: vite dev support, Workers, bun --smol, WebSocket.ping(), structuredClone(), serialize() and better Node.js compatibility date: "2023-07-21T00:57:49+00:00" author: jarred draft: false --- We're pleased to announce Bun v0.7.0, a big leap forward in terms of Node.js compatibility. {% callout %} We're hiring C/C++ and Zig engineers to build the future of JavaScript! [Join our team →](/careers) {% /callout %} Bun is an incredibly fast JavaScript runtime, bundler, transpiler, and package manager — all in one. Over the past couple months, we've been releasing a lot of changes to Bun recently, here's a recap in case you missed it: - [`v0.6.10`](/blog/bun-v0.6.10) - `fs.watch()`, `bun install` bug fixes, `bun test` features, and improved CommonJS support - [`v0.6.11`](/blog/bun-v0.6.10) - Addressed a release build issue from `v0.6.10`. - [`v0.6.12`](/blog/bun-v0.6.12) - Sourcemap support in `Error.stack`, `Bun.file().exists()`, and Node.js bug fixes. - [`v0.6.13`](/blog/bun-v0.6.13) - Implemented mock `Date`, faster base64 encoding, and fixes for `WebSocket` and `node:tls`. - [`v0.6.14`](/blog/bun-v0.6.14) - `process.memoryUsage()`, `process.cpuUsage()`, `process.on('beforeExit', cb)`, `process.on('exit', cb)` and crash fixes To install Bun: {% codetabs %} ```sh#curl $ curl -fsSL https://bun.sh/install | bash ``` ```sh#npm $ npm install -g bun ``` ```sh#brew $ brew tap oven-sh/bun $ brew install bun ``` ```sh#docker $ docker pull oven/bun $ docker run --rm --init --ulimit memlock=-1:-1 oven/bun ``` {% /codetabs %} To upgrade Bun: ```sh $ bun upgrade ``` ## Vite support {% callout %} _Support is still experimental and non-optimized._ Vite does not use Bun's bundler, module resolver, or transpiler, even when run with Bun. {% /callout %} With the recent strides towards Node.js API compatibilty, Bun can now run [`vite dev`](https://vitejs.dev/), thanks to [@paperclover](https://github.com/paperclover)! This is one of Bun's [most upvoted issues](https://github.com/oven-sh/bun/issues/250). To try this with one of Vite's starter projects, use `bunx`: ```sh $ bunx create-vite myapp $ cd myapp $ bun install ``` Then start the dev server. ```sh $ bun --bun vite dev ``` {% callout %} **Why `--bun`?** The `--bun` flag tells Bun to override the `#! /usr/bin/env node` shebang in the `vite` CLI and execute the file with Bun instead of Node.js. In a future release this will be the default behavior. {% /callout %} {% image src="https://user-images.githubusercontent.com/709451/254804727-725bf67c-c60f-4eec-b472-07d52b650a93.gif" caption="Hot module reloading with Vite" /%} This is a great way to develop frontend code with Bun's APIs on the server when building frontend apps. Note: if you run `bun vite dev` without `-b` or `--bun`, it will still run in Node.js as `vite`'s CLI specifies `#!/usr/bin/env node` at the top which tells Bun (and other software on your computer) to run it in Node.js. ## Concurrency with `Worker` Bun now supports [`Worker`](https://developer.mozilla.org/en-US/docs/Web/API/Worker) which allows you to run another JavaScript instance in a separate thread. In Bun, workers support ES Modules, CommonJS, TypeScript, JSX, and the rest of Bun's features with no extra configuration. As in browsers, `Worker` is a global class. To create a worker from the main thread: ```ts#main.ts const worker = new Worker("./worker.ts"); worker.addEventListener("message", (event: MessageEvent) => { console.log("Message from worker:", event.data); }); worker.postMessage("Hello from main thread!"); ``` On the worker thread: ```ts#worker.ts addEventListener("message", (event: MessageEvent) => { console.log("Message from main thread:", event.data); postMessage("Hello from worker thread!"); }); ``` {% callout %} This release _does not_ include support for the `node:worker_threads` module, but this unblocks the work necessary for us to implement it in Bun. {% /callout %} The following globals have been added to Bun: - `postMessage` - `addEventListener` - `removeEventListener` - `onmessage` (getter/setter) Refer to [Docs > API > Workers](/docs/api/workers) to learn more about using `Worker` in Bun. ### Using `comlink` with Bun The popular [`comlink`](https://github.com/GoogleChromeLabs/comlink) package works in Bun without changes. This library makes it easier to share functions and state between main and worker threads. {% details summary="Comlink usage example" %} The main thread: ```ts#main.ts import * as Comlink from "comlink"; const worker = new Worker("./worker.ts"); // WebWorkers use `postMessage` and therefore work with Comlink. const obj = Comlink.wrap(worker); alert(`Counter: ${await obj.counter}`); await obj.inc(); alert(`Counter: ${await obj.counter}`); ``` The worker thread: ```ts#worker.ts import * as Comlink from "comlink"; const obj = { counter: 0, inc() { this.counter++; }, }; Comlink.expose(obj); ``` {% /details %} ### `structuredClone()` support As in browsers, `postMessage` serializes messages using the _structured clone algorithm_. Bun now exposes this via the Web-standard[`structuredClone()`](https://developer.mozilla.org/en-US/docs/Web/API/structuredClone) function, which provides a mechanism for deep-cloning objects. It is similar to `JSON.parse(JSON.stringify(obj))`, but it supports more types. ```ts const obj = { a: 1, b: 2 }; const clone = structuredClone(obj); ``` ## `AsyncLocalStorage` support Bun now implements `AsyncLocalStorage` from the `node:async_hooks` module. This provides a mechanism for passing contextual data through a chain of asynchronous code. This is a big step towards supporting Next.js and other frameworks that rely on this module. ```ts import { AsyncLocalStorage } from "node:async_hooks"; const requestId = new AsyncLocalStorage(); let lastId = 0; Bun.serve({ fetch(request) { lastId++; // Run the callback with 'requestId' set. async_hooks will preserve // this value through any chain of asynchronous code. return requestId.run(lastId, async () => { console.log(`Request ID: ${requestId.getStore()}`); await Bun.sleep(500); // Even if new requests mutate 'lastId', 'requestId' is still preserved. return new Response(`Request ID: ${requestId.getStore()}`); }); }, }); ``` ## Reduce memory usage with `bun --smol` `bun --smol` is a new CLI flag which configures the JavaScriptCore heap size to be smaller and grow slower, at a cost to runtime performance. This is useful for running Bun in memory-constrained environments. {% raw %}

The next version of bun gets the "--smol" flag, which reduces memory usage at a slight cost to performance pic.twitter.com/9cw9vylrur

— Jarred Sumner (@jarredsumner) July 17, 2023
{% /raw %} To avoid setting the flag manually, you can set this as a default in `bunfig.toml`. ```toml#bunfig.toml smol = true [test] # set it only for tests, if you want smol = true ``` ## `--bail` in `bun test` Running `bun test` with `--bail=1` will exit after the first test failure. ```sh $ bun test --bail 1 bun test v0.7.0 ✓ test1 [0.02ms] test2.test.js: 1 | import {test, expect} from 'bun:test'; 2 | 3 | test('test2', () => { 4 | expect(2).toEqual(3); ^ error: expect(received).toEqual(expected) Expected: 3 Received: 2 at /Users/colinmcd94/Documents/bun/fun/test/test2.test.js:13:8 ✗ test2 [0.18ms] Ran 2 tests across 2 files. [8.00ms] Bailed out after 1 failures ``` This is useful for CI environments or when you want to stop running tests after the first failure. Thanks to [@TiranexDev](https://github.com/TiranexDev) for landing this improvement! ## `Bun.readableStreamToFormData()` Bun now exposes a helper for converting a [ReadableStream](https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream) into [FormData](https://developer.mozilla.org/en-US/docs/Web/API/FormData). It supports multipart form data. ```ts import { readableStreamToFormData } from "bun"; // without dashes const boundary = "WebKitFormBoundary" + Math.random().toString(16).slice(2); const myStream = getStreamFromSomewhere(); // ... const formData = await Bun.readableStreamToFormData(stream, boundary); formData.get("foo"); // "bar" ``` It also supports URL-encoded form data: ```ts import { readableStreamToFormData } from "bun"; const stream = new Response("hello=123").body; const formData = await readableStreamToFormData(stream); formData.get("hello"); // "123" ``` We added this to help fix a bug causing `request.formData()` and `response.formData()` to hang when the body was a `ReadableStream` from JavaScript. ## `serialize` and `deserialize` in `bun:jsc` The `bun:jsc` module now exports `serialize()` and `deserialize()`, which convert JavaScript objects to `ArrayBuffer` and back. ```ts import { serialize, deserialize } from "bun:jsc"; import { deepEquals } from "bun"; const obj = { a: 1, b: 2 }; const buffer = serialize(obj); const clone = deserialize(buffer); if (deepEquals(obj, clone)) { console.log("They are equal!"); } ``` The `node:v8` module exports these same functions, for compatibility with existing libraries that serialize/deserialize data between processes. ## `WebSocket` improvements You can now manually send & receive WebSocket `ping` and `pong` frames. ```ts const ws = new WebSocket("wss://echo.websocket.org"); ws.addEventListener("pong", () => { console.log("Received pong"); }); ws.ping(); ``` This applies to both `ServerWebSocket` and `WebSocket`. ### `nodebuffer` is now the default `binaryType` By default, the `binaryType` for `WebSocket` and `ServerWebSocket` in Bun is now `nodebuffer` This means that binary data frames in `WebSocket` will be `Buffer` instances, instead of `ArrayBuffer` (as before). This is to match the bahavior of the `ws` package. ```ts const ws = new WebSocket("wss://echo.websocket.org"); ws.addEventListener("message", (event: MessageEvent) => { console.log(event.data instanceof Buffer); // true }); ``` To change it back to `ArrayBuffer`, set `ws.binaryType = "arraybuffer"`. ```ts const ws = new WebSocket("wss://echo.websocket.org"); ws.binaryType = "arraybuffer"; ws.addEventListener("message", (event: MessageEvent) => { event.data; // ArrayBuffer }); ``` (Note that in browsers it is `Blob` by default.) ### Close reasons propagate correctly now A bug was fixed where `WebSocket` would not propagate close reasons from third-party servers correctly. Thanks to [@Electroid](https://github.com/electroid) for landing these improvements! ## Node.js compatibility improvements This release adds several additional improvements to Node.js compatibility. ### Improvements to `TLSSocket` from `node:tls` The following methods were implemented on the `TLSSocket` class. Thanks to [@cirospaciari](https://github.com/cirospaciari) for landing these improvements in [`#3596`](https://github.com/oven-sh/bun/pull/3596). - `.getPeerFinished()` - `.getFinished()` - `.getProtocol()` - `.getSharedSigalgs()` - `.isSessionReused()` - `.exportKeyingMaterial()` - `.setMaxSendFragment()` - `.getPeerCertificate()` - `.getCertificate()` - `.enableTrace()` - `.disableRenegotiation()` - `.getCipher()` - `.getEphemeralKeyInfo()` - `.getTLSTicket()` - `.getSession()` - `.setSession()` ### `base64url` hashes are no longer `data:` urls Previously, Bun would prepend `data:base64,` to the output of `crypto.createHash("sha256").digest("base64url")`. This is not what Node.js does, and it was causing issues with libraries that expected the output to be the same string as Node.js. ```js crypto.createHash("sha256").update("abc").digest("base64url"); // Node.js: "ungWv48Bz-pBQUDeXa4iI7ADYaOWF3qctBD_YfIAFa0" // Bun v0.7.0: "ungWv48Bz-pBQUDeXa4iI7ADYaOWF3qctBD_YfIAFa0" // <= Bun v0.6.14: "data:base64,ungWv48Bz-pBQUDeXa4iI7ADYaOWF3qctBD_YfIAFa0=" ``` ### Terminal dimensions with `process.stdout.columns` and `process.stdout.rows` `process.stdout` and `process.stderr` now support reading the terminal window's dimensions. ```ts const { columns, rows } = process.stdout; const [columns, rows] = process.stdout.getWindowSize(); const { columns, rows } = process.stderr; const [columns, rows] = process.stderr.getWindowSize(); ``` You can also use `process.stdout.getWindowSize()` if you want both dimensions at once. ## Bugfixes [`#3656`](https://github.com/oven-sh/bun/pull/3656) **A memory leak** in await `new Response(latin1String).arrayBuffer()` and `await Response.json(obj).json()` has been fixed. After: ```js cpu: Apple M1 Max runtime: bun 0.7.0 (arm64-darwin) benchmark time (avg) (min … max) p75 p99 p995 --------------------------------------------------------------------------------------------------- ----------------------------- new Response().arrayBuffer() (new string each call, latin1) 12.9 µs/iter (625 ns … 4.18 ms) 1 µs 567.17 µs 711.79 µs new Response().arrayBuffer() (new string each call, utf16) 12.85 µs/iter (1.67 µs … 1.56 ms) 2.17 µs 462.75 µs 621.13 µs new Response().arrayBuffer() (existing string, latin1) 6.53 µs/iter (6.21 µs … 7.07 µs) 6.64 µs 7.07 µs 7.07 µs Peak memory usage: 49 MB ``` Before: ```js cpu: Apple M1 Max runtime: bun 0.7.0 (arm64-darwin) benchmark time (avg) (min … max) p75 p99 p995 --------------------------------------------------------------------------------------------------- ----------------------------- new Response().arrayBuffer() (new string each call, latin1) 13.51 µs/iter (541 ns … 3.2 ms) 1.92 µs 553.42 µs 709.92 µs new Response().arrayBuffer() (new string each call, utf16) 13.07 µs/iter (1.71 µs … 3.43 ms) 2.13 µs 451.21 µs 651.67 µs new Response().arrayBuffer() (existing string, latin1) 6.25 µs/iter (5.79 µs … 6.81 µs) 6.4 µs 6.81 µs 6.81 µs Peak memory usage: 292 MB ``` [`#3659`](https://github.com/oven-sh/bun/issues/3659) A **module resolution bug** causing the `graphql` package to import both CommonJS and ESM versions of the same modules has been fixed. This was fixed by aligning the package.json main field order closer to what Node.js does. ``` error: Cannot use GraphQLScalarType "String" from another module or realm. Ensure that there is only one instance of "graphql" in the node_modules directory. If different versions of "graphql" are the dependencies of other relied on modules, use "resolutions" to ensure only one version is installed. https://yarnpkg.com/en/docs/selective-version-resolutions Duplicate "graphql" modules cannot be used at the same time since different versions may have different capabilities and behavior. The data from one version used in the function from another could produce confusing and spurious results. ``` [`#3663`](https://github.com/oven-sh/bun/pull/3663) A **bug in bun:test lifecycle hooks** caused `beforeAll` and `afterAll` to not run when no tests were defined in a scope. This has been fixed. [`#3670`](https://github.com/oven-sh/bun/issues/3670) A **bug when .env pointed to a directory** caused Bun to crash. This has been fixed. [`#3682`](https://github.com/oven-sh/bun/issues/3682) A **TypeScript parser bug related to ternaries with spread operators** has been fixed ### Changelog {% table %} --- - [#3253](https://github.com/oven-sh/bun/pull/3253) - feat(bun/test): Implement "bail" option for "bun test" by [@TiranexDev](https://github.com/TiranexDev) --- - [#3608](https://github.com/oven-sh/bun/pull/3608) - Improve our internal typedefs by [@paperclover](https://github.com/paperclover) --- - [#3257](https://github.com/oven-sh/bun/pull/3257) - Improvements to `WebSocket` and `ServerWebSocket` by [@Electroid](https://github.com/Electroid) --- - [#3630](https://github.com/oven-sh/bun/pull/3630) - $npm_lifecycle_event should have the value of the last call by [@TiranexDev](https://github.com/TiranexDev) --- - [#3631](https://github.com/oven-sh/bun/pull/3631) - Update docs/types for process by [@colinhacks](https://github.com/colinhacks) --- - [#3637](https://github.com/oven-sh/bun/pull/3637) - structured clone by [@dylan-conway](https://github.com/dylan-conway) --- - [#3650](https://github.com/oven-sh/bun/pull/3650) - docs: add one missing line in typescript.md by [@capaj](https://github.com/capaj) --- - [#3643](https://github.com/oven-sh/bun/pull/3643) - Fixes #3641 by [@Jarred-Sumner](https://github.com/Jarred-Sumner) --- - [#3614](https://github.com/oven-sh/bun/pull/3614) - Support `napi_wrap` in constructors by [@Jarred-Sumner](https://github.com/Jarred-Sumner) --- - [#3645](https://github.com/oven-sh/bun/pull/3645) - Implement Workers by [@Jarred-Sumner](https://github.com/Jarred-Sumner) --- - [#3654](https://github.com/oven-sh/bun/pull/3654) - Fixes base64url encoding for crypto by [@Jarred-Sumner](https://github.com/Jarred-Sumner) --- - [#3655](https://github.com/oven-sh/bun/pull/3655) - 20% faster `deserialize` for structuredClone / postMessage with objects by [@Jarred-Sumner](https://github.com/Jarred-Sumner) --- - [#3626](https://github.com/oven-sh/bun/pull/3626) - workaround `readable-stream` compatibility by [@alexlamsl](https://github.com/alexlamsl) --- - [#3662](https://github.com/oven-sh/bun/pull/3662) - [install] handle duplicated workspace declarations gracefully by [@alexlamsl](https://github.com/alexlamsl) --- - [#3664](https://github.com/oven-sh/bun/pull/3664) - package json `main` field extension order by [@dylan-conway](https://github.com/dylan-conway) --- - [#3596](https://github.com/oven-sh/bun/pull/3596) - [tls] General compatibility improvements by [@cirospaciari](https://github.com/cirospaciari) --- - [#3667](https://github.com/oven-sh/bun/pull/3667) - zig upgrade by [@dylan-conway](https://github.com/dylan-conway) --- - [#3671](https://github.com/oven-sh/bun/pull/3671) - fix(tls) patch checkServerIdentity by [@cirospaciari](https://github.com/cirospaciari) --- - [#3672](https://github.com/oven-sh/bun/pull/3672) - feature(constants) add constants/node:constants module and tests(prisma) use prima 5.0.0 + use same connection for postgres, add prisma mssql (disabled for now) by [@cirospaciari](https://github.com/cirospaciari) --- - [#3678](https://github.com/oven-sh/bun/pull/3678) - Better error for workspace dependency not found by [@Jarred-Sumner](https://github.com/Jarred-Sumner) --- - [#3683](https://github.com/oven-sh/bun/pull/3683) - move constants module to cpp by [@cirospaciari](https://github.com/cirospaciari) --- - [#3687](https://github.com/oven-sh/bun/pull/3687) - fix #3682 by [@dylan-conway](https://github.com/dylan-conway) --- - [#3680](https://github.com/oven-sh/bun/pull/3680) - fix createDecipheriv by [@cirospaciari](https://github.com/cirospaciari) --- - [#3688](https://github.com/oven-sh/bun/pull/3688) - update root certificates and add tls.rootCertificates by [@cirospaciari](https://github.com/cirospaciari) --- - [#3089](https://github.com/oven-sh/bun/pull/3089) - Implement `AsyncLocalStorage` by [@paperclover](https://github.com/paperclover) --- - [#3693](https://github.com/oven-sh/bun/pull/3693) - Fix browser bundled string_decoder by [@paperclover](https://github.com/paperclover) --- - [#3694](https://github.com/oven-sh/bun/pull/3694) - Fix vite by [@paperclover](https://github.com/paperclover) --- - [#3698](https://github.com/oven-sh/bun/pull/3698) - Fixes #3670 by [@Jarred-Sumner](https://github.com/Jarred-Sumner) --- - [#3697](https://github.com/oven-sh/bun/pull/3697) - Support streams in response.formData() & request.formData, introduce Bun.readableStreamToFormData() by [@Jarred-Sumner](https://github.com/Jarred-Sumner) --- - [#3706](https://github.com/oven-sh/bun/pull/3706) - Improve types for FFI number types by [@colinhacks](https://github.com/colinhacks) --- - [#3707](https://github.com/oven-sh/bun/pull/3707) - fix start delay on Worker by [@cirospaciari](https://github.com/cirospaciari) --- - [#3709](https://github.com/oven-sh/bun/pull/3709) - set `_preload_modules` to empty array by [@dylan-conway](https://github.com/dylan-conway) --- - [#3708](https://github.com/oven-sh/bun/pull/3708) - fix 3702 by [@dylan-conway](https://github.com/dylan-conway) --- - [#3692](https://github.com/oven-sh/bun/pull/3692) - Pass constructor arguments to TextDecoder by [@Parzival-3141](https://github.com/Parzival-3141) --- - [#3711](https://github.com/oven-sh/bun/pull/3711) - Fix builtins generator `$lazy` by [@paperclover](https://github.com/paperclover) --- - [#3710](https://github.com/oven-sh/bun/pull/3710) - fix directory caching with workaround by [@paperclover](https://github.com/paperclover) --- - [#3713](https://github.com/oven-sh/bun/pull/3713) - Fix builtins again by [@paperclover](https://github.com/paperclover) --- - [#3714](https://github.com/oven-sh/bun/pull/3714) - fix process.exit status code handling by [@paperclover](https://github.com/paperclover) --- - [#3715](https://github.com/oven-sh/bun/pull/3715) - fix `isFIFO` by [@dylan-conway](https://github.com/dylan-conway) --- - [#3717](https://github.com/oven-sh/bun/pull/3717) - string escape edgecase by [@dylan-conway](https://github.com/dylan-conway) --- {% /table %}