.{stdout,stderr}.log` | | Windows | `schtasks` | Event Viewer → TaskScheduler | Re-registering with the same title overwrites the existing job in-place. ## `Bun.sliceAnsi` — ANSI & grapheme-aware string slicing  A new built-in that replaces both the [`slice-ansi`](https://www.npmjs.com/package/slice-ansi) and [`cli-truncate`](https://www.npmjs.com/package/cli-truncate) npm packages. `Bun.sliceAnsi` slices strings by terminal column width while preserving ANSI escape codes (SGR colors, OSC 8 hyperlinks) and respecting grapheme cluster boundaries (emoji, combining marks, flags). ```js // Plain slice (replaces slice-ansi) Bun.sliceAnsi("\x1b[31mhello\x1b[39m", 1, 4); // "\x1b[31mell\x1b[39m" // Truncation with ellipsis (replaces cli-truncate) Bun.sliceAnsi("unicorn", 0, 4, "…"); // "uni…" Bun.sliceAnsi("unicorn", -4, undefined, "…"); // "…orn" ``` The ellipsis is emitted **inside** active SGR styles (inherits color/bold) so truncated text stays visually consistent, but **outside** hyperlinks to avoid broken links. Negative indices are supported for slicing from the end. An optional `{ ambiguousIsNarrow }` option is available for controlling East Asian ambiguous width behavior, matching `Bun.stringWidth` and `Bun.wrapAnsi`. ### Performance Uses a three-tier dispatch strategy: - **SIMD ASCII fast path** — pure ASCII input is handled with a single SIMD scan and zero-copy when nothing is cut - **Single-pass streaming** — non-negative indices (the common case) walk the input once with stack-only allocation - **Two-pass for negative indices** — computes total width first, then emits ## `Bun.markdown.render()` now passes richer metadata to `listItem` and `list` callbacks The `listItem` callback in `Bun.markdown.render()` now receives `index`, `depth`, `ordered`, and `start` in its metadata object, and the `list` callback now includes `depth`. Previously, `listItem` only received `checked` (and only for task list items), making it impossible to know an item's position, nesting level, or parent list type without workarounds. This makes it straightforward to implement custom list markers like nested numbering schemes (`1.` / `a.` / `i.`) without regex post-processing: ```ts const result = Bun.markdown.render( "1. first\n 1. sub-a\n 2. sub-b\n2. second", { listItem: (children, { index, depth, ordered, start }) => { const n = (start ?? 1) + index; const marker = !ordered ? "-" : depth === 0 ? `${n}.` : `${String.fromCharCode(96 + n)}.`; return " ".repeat(depth) + marker + " " + children.trimEnd() + "\n"; }, list: (children) => "\n" + children, }, ); // 1. first // a. sub-a // b. sub-b // 2. second ``` The full `listItem` meta shape is now: | Property | Type | Description | | --------- | ---------------------- | ------------------------------------------------------- | | `index` | `number` | 0-based position within the parent list | | `depth` | `number` | Nesting level of the parent list (0 = top-level) | | `ordered` | `boolean` | Whether the parent list is ordered | | `start` | `number \| undefined` | Start number of the parent list (only set when ordered) | | `checked` | `boolean \| undefined` | Task list state (only set for `- [x]` / `- [ ]` items) | **Breaking change:** The `listItem` callback now **always** receives the meta object (previously it was only passed for task list items). `start` and `checked` are `undefined` when not applicable, keeping the object shape fixed for monomorphic inline caches. Meta objects use cached JSC structures internally, adding ~0.7ns per object overhead — effectively free. ## `--path-ignore-patterns` for `bun test`  You can now exclude files and directories from test discovery using glob patterns with the new `--path-ignore-patterns` flag or `test.pathIgnorePatterns` in `bunfig.toml`. This is useful when your project contains submodules, vendored code, or other directories with `*.test.ts` files that you don't want `bun test` to pick up. Matched directories are pruned during scanning, so their contents are never traversed — ignoring a large directory tree is efficient. ```toml # bunfig.toml [test] pathIgnorePatterns = [ "vendor/**", "submodules/**", "fixtures/**", "**/test-data/**" ] ``` Or via the command line: ```bash $ bun test --path-ignore-patterns 'vendor/**' --path-ignore-patterns 'fixtures/**' ``` Command-line `--path-ignore-patterns` flags override the `bunfig.toml` value entirely — the two are not merged. Thanks to @ctjlewis and @alii for the contribution! ## Fixed `dgram` UDP socket bugs on macOS  Fixed three bugs in UDP socket creation that caused `dgram` sockets to silently fail on macOS: - **`reusePort` now works on macOS**: The `reusePort: true` option was previously gated to Linux only. It now works on any platform that supports `SO_REUSEPORT`. - **Implicit bind-on-send works on macOS**: Calling `send()` on an unbound UDP socket should implicitly bind to `0.0.0.0` on a random port (matching Node.js behavior). Hardcoded Linux errno values (`92` instead of the `ENOPROTOOPT` macro) prevented IPv4 fallback paths from being taken on macOS, where `ENOPROTOOPT` is `42`. - **Socket fd leak on failure**: When `setsockopt` for reuse failed, the socket file descriptor was leaked and no diagnostic errno was propagated, producing generic "Failed to bind socket" errors. This affected real-world libraries like [`k-rpc`](https://github.com/mafintosh/k-rpc) (used by [`bittorrent-dht`](https://github.com/webtorrent/bittorrent-dht)) that rely on implicit binding behavior. ```js import dgram from "dgram"; const socket = dgram.createSocket("udp4"); // This now correctly auto-binds on macOS, matching Node.js behavior socket.send(Buffer.from("hello"), 0, 5, 41234, "127.0.0.1", (err) => { if (err) console.error("send error:", err); else console.log("sent successfully"); const addr = socket.address(); console.log("bound to:", addr); // Shows auto-assigned port socket.close(); }); ``` ## Native ARM64 shim for Windows `node_modules/.bin` binaries  The `bun_shim_impl.exe` used for `node_modules/.bin/*` on Windows was previously hardcoded to x86_64, meaning every package binary invocation on Windows ARM64 ran under x64 emulation. The shim is now compiled natively for aarch64 when building Bun for Windows ARM64, removing the emulation overhead. Thanks to @dylan-conway for the contribution! ## Bugfixes ### Node.js compatibility improvements - Fixed: An operator precedence bug in native readable streams caused `0 < MIN_BUFFER_SIZE` to be evaluated before the `??` operator, resulting in excessive memory allocation when processing stream chunks - Fixed: Custom `lookup` function in Node.js `http`/`https` client (e.g. via axios) breaking TLS certificate verification with `ERR_TLS_CERT_ALTNAME_INVALID` or `unknown certificate verification error`. When a custom DNS lookup resolved a hostname to an IP address, the original hostname was lost, causing TLS SNI and certificate verification to fail. - Fixed: `fs.openSync` and `fs.promises.open` throwing `EINVAL` on Windows when passed numeric flags from `fs.constants` (e.g. `O_CREAT | O_TRUNC | O_WRONLY`). The `fs.constants` values on Windows use native MSVC values which differ from Bun's internal representation, causing flags like `O_CREAT` to be silently dropped. This also fixes `UV_FS_O_FILEMAP` support, which unbreaks packages like `tar@7` (used by `npm`, `giget`, and others) that silently failed to extract files on Windows. (@Hona) - Fixed: `fs.stat` truncating sub-millisecond precision from `mtimeMs`, `atimeMs`, `ctimeMs`, and `birthtimeMs` properties, now returning fractional milliseconds matching Node.js behavior - Fixed: `fs.watch()` crash on Windows when a failed watch is retried on the same path - Fixed: a crash in `fs.watchFile` - Fixed: `node:fs` functions crashing with certain inputs - Fixed: crash (`cast causes pointer to be null`) on Windows when `fs.realpathSync` or `fs.readlink` encountered certain edge-case filesystem configurations like ramdisk volumes, substituted drives, or standalone executables in unusual locations - Fixed: `console.Console` returning `undefined` permanently after being accessed during a near-stack-overflow condition (@sosukesuzuki) - Fixed: `Buffer.compare` not properly validating `targetEnd` and `sourceEnd` offset bounds, where certain combinations of start/end values could bypass range checks instead of throwing `ERR_OUT_OF_RANGE` as Node.js does - Fixed: rare crash in `Buffer.indexOf`, `Buffer.lastIndexOf`, and `Buffer.includes` - Fixed: buffer overflow in path-handling code - Fixed: `process.off("SIGxxx", handler)` removing one of multiple signal listeners would incorrectly uninstall the OS signal handler, causing remaining listeners to stop receiving signals - Fixed: `execFileSync` and `execSync` errors containing a self-referencing cycle (`err.error === err`) that caused `JSON.stringify(err)` to throw - Fixed: `spawnSync` could accidentally drain the global microtask queue, executing user JavaScript during what should be a synchronous, blocking call. - Fixed: missing BoringSSL error clearing in `crypto.createPrivateKey()` - Fixed: Crash in `crypto.Hash` `update()`/`digest()` caused by missing `this` validation, a GC hazard on input strings during encoding conversion, and reading from detached buffers. Now properly throws `ERR_INVALID_THIS` and `ERR_INVALID_STATE` instead of crashing. - Fixed: crashs when calling native crypto/stream prototype methods (like `Hmac.digest()`, `DiffieHellmanGroup.verifyError`) with an invalid `this` value — now correctly throws `ERR_INVALID_THIS` instead of crashing - Fixed: `X509Certificate.prototype` was `undefined`, which prevented subclassing with `class Foo extends X509Certificate {}` (@sosukesuzuki) - Fixed: `getPeerCertificate()` returning `undefined` instead of `{}` when no peer certificate is available, which caused `checkServerIdentity()` to crash with `TypeError: Cannot destructure property 'subject' from null or undefined value` during TLS handshakes — most notably when connecting to MongoDB Atlas clusters - Fixed: hypothetical out of bounds read/write in native zlib `write()`/`writeSync()` where user-controlled offset and length parameters were not properly validated in production builds. These now correctly throw `ERR_OUT_OF_RANGE`, `ERR_INVALID_ARG_TYPE`, and other appropriate errors. - Fixed: `dgram.createSocket()` incorrectly set `SO_REUSEADDR` on all UDP sockets, allowing multiple processes to silently bind to the same port without throwing `EADDRINUSE` — diverging from Node.js behavior. `SO_REUSEADDR` is now only applied when `reuseAddr: true` is explicitly passed. - Fixed: a latent GC safety issue in `node:vm` modules where a garbage collection cycle during object construction could lead to a crash (@sosukesuzuki) - Fixed: `structuredClone()` throwing `DataCloneError` on objects created via `napi_create_object`, matching Node.js behavior (@dylan-conway) - Fixed: `node:http2` client streams stalling after receiving 65,535 bytes when using `setLocalWindowSize()` — the method updated the internal connection window size but never sent a `WINDOW_UPDATE` frame to the peer, causing the server to stop sending data once the default window was exhausted - Fixed: `node:http2` `getPackedSettings`, `getUnpackedSettings`, and `getDefaultSettings` now match Node.js behavior, including support for `enableConnectProtocol`, `customSettings`, correct `enablePush` default, and proper `ERR_HTTP2_INVALID_SETTING_VALUE` error codes (@cirospaciari) - Fixed: crash that could occur on exit when using NAPI native addon modules (such as `skia-canvas`) on Windows - Fixed: bug in libuv on Windows that could cause pipe data loss when reading from subprocess pipes ### Bun APIs - Fixed PgBouncer incompatibility with `sql.prepare(false)` queries - Fixed: `Bun.file().text()` and similar async read methods not keeping event loop alive when an error errors - Fixed: Incorrect `Bun.file()` async read error paths on Windows - Fixed: `Bun.file().stat()` and `Bun.file().delete()` corrupting file paths containing non-ASCII UTF-8 characters (e.g., German umlauts, Japanese characters, emoji), causing `ENOENT` errors due to double-encoding - Fixed: `Bun.stdin.stream()` and `Bun.stdin.text()` returning empty on Linux after calling `Bun.stdin.exists()` or accessing `Bun.stdin.size` - Fixed: `Bun.JSONL.parseChunk(input, start, end)` now honors `start`/`end` offsets when `input` is a string. - Fixed: `S3File.slice(0, N).stream()` ignoring the slice range and downloading the entire file instead of only the requested byte range - Fixed: `bun:sql` panicking with "integer does not fit in destination type" when a PostgreSQL query exceeded the 65,535 parameter limit (e.g. batch inserting 7,000 rows × 10 columns). Now throws a descriptive `PostgresError` with code `ERR_POSTGRES_TOO_MANY_PARAMETERS` and a hint to reduce batch size - Fixed: Valkey RESP protocol parser no longer crashes with a stack overflow on deeply nested server responses by enforcing a maximum nesting depth of 128 for aggregate types (@dylan-conway) - Fixed: `Bun.Transpiler` ignoring `experimentalDecorators: true` and `emitDecoratorMetadata: true` from tsconfig, always emitting TC39-style decorators instead of legacy TypeScript decorators. This broke frameworks like Angular that rely on legacy decorator calling conventions in JIT mode. - Fixed: `Bun.Transpiler.scanImports()` and `Bun.Transpiler.scan()` ignoring the `trimUnusedImports` option — unused imports were only being trimmed by `transformSync()` - Fixed: memory leak in `Bun.Transpiler` when using a custom `tsconfig` with async `transform()` calls. After the first `await transpiler.transform()`, subsequent calls could read freed memory or double-free the tsconfig pointer, potentially causing crashes. - Fixed: `emitDecoratorMetadata: true` in tsconfig.json without `experimentalDecorators: true` incorrectly used TC39 standard decorators instead of legacy decorator semantics, causing NestJS, TypeORM, Angular, and other legacy-decorator frameworks to crash with `descriptor.value` undefined - Fixed: Breakpoints landing at wrong line numbers when debugging files over 50KB in VSCode's debug terminal (`BUN_INSPECT` env var). The runtime transpiler cache was not being disabled when the debugger was activated via the `BUN_INSPECT` environment variable (as opposed to `--inspect` CLI flags), causing cached output without inline source maps to be used. (@alii) - Fixed: HTML-referenced assets (favicons, images, etc.) returning 404 when served with `Bun.serve()` because they were missing from the bundle manifest's `files` array despite being correctly emitted to disk - Fixed `ReadableStream` with `type: "direct"` incorrectly calling the user's `cancel` callback on normal stream completion - Fixed: Empty string arguments in Bun shell - Fixed: DoS in `Bun.stringWidth` - Fixed: `Bun.stringWidth` grapheme bug: ANSI escape bytes were incorrectly included in grapheme break tracking ### Web APIs - Fixed: incorrect value in `WebSocket.prototype.protocol` in certain cases - Fixed: `ws.ping()` and `ws.pong()` called without arguments incorrectly sent non-empty payloads instead of empty control frames, causing disconnections with strict WebSocket servers (e.g. Binance) that validate pong payloads match ping payloads (@gaowhen) - Fixed: WebSocket client now validates the `Sec-WebSocket-Accept` header value during the upgrade handshake per RFC 6455 §4.2.2, rejecting connections where the server returns a stale or mismatched response - Fixed: `Request.formData()` truncating small binary files with null bytes - Fixed: a crash when calling `fetch()` using a very large number of headers - Fixed: crash in fetch with TLS proxies in certain cases - Fixed: Edgecase with pipelined HTTP requests with no headers - Fixed: HTTP header value incorrect stripping for certain cases - Hardened Bun's HTTP server against malformed chunked transfer requests. Thanks to @sim1222 for reporting issues. - Fixed: CRLF injection vulnerability in `ServerResponse.prototype.writeEarlyHints` where header names and values were written to the socket without validation, allowing HTTP response splitting attacks - Fixed: WebSocket connections dropping over proxy tunnels with bidirectional traffic ### bun install - Fixed: `bun install` hanging indefinitely or silently skipping processing when a security scanner is enabled and the project has more than ~790 packages. The package list is now sent to the scanner subprocess via an IPC pipe instead of command-line arguments, avoiding OS argument length limits - Fixed: `bun install` hanging indefinitely (~300 seconds per dependency) when using an HTTP proxy (`http_proxy`/`https_proxy`) with cached packages that return `304 Not Modified` through a CONNECT tunnel (@WhiteMinds) - Fixed: Non-deterministic `bun install` bug where transitive peer dependencies were left unresolved when all manifest loads were synchronous (e.g., warm cache with valid `Cache-Control: max-age`), causing missing peer dependency symlinks with `--linker=isolated` (@dylan-conway) - Fixed: `.npmrc` auth token matching only comparing hostnames - Fixed: `bun install` silently exiting with code 1 when the security scanner encounters an error, making failures impossible to debug (especially in CI). All error paths now print descriptive messages to stderr. - Fixed: `bun install` now shows an accurate error message when a `file:` dependency path is missing (e.g., due to a stale lockfile), instead of the misleading "Bun could not find a package.json file to install from" message. The new error clearly identifies the dependency and the exact path that was not found. - Fixed: `bun update -i` select all ('A' key) now correctly updates packages instead of showing "No packages selected for update" - Fixed: `bun pack` and `bun publish` using stale `version` and `name` from `package.json` when lifecycle scripts (`prepublishOnly`, `prepack`, `prepare`) modify them during execution. Previously, the tarball filename and publish registry metadata would use the original values captured before scripts ran. (@dylan-conway) - Fixed: `bun bun.lockb | head` no longer prints an internal `BrokenPipe` error message instead of exiting silently ### JavaScript bundler - Fixed: `bun build --compile --bytecode --format=esm` crashing at runtime with "Cannot find module" errors when barrel-optimized packages (those with `"sideEffects": false`) had unused re-exports recorded as external dependencies in bytecode ModuleInfo (@Jarred-Sumner) - Fixed: `import Bun from 'bun'` returning `undefined` when bundled with `--bytecode` flag. The CJS lowering pass was incorrectly generating `globalThis.Bun.default` instead of `globalThis.Bun` for default imports. - Fixed: Bundler dropping exports when barrel files with `sideEffects: false` re-export namespace imports (`import * as X from './mod'; export { X }`), causing `ReferenceError` for the re-exported bindings at runtime - Fixed: Bundler barrel optimization incorrectly dropped exports needed by dynamic `import()` when the same barrel was also referenced by a static named import, producing invalid JS with undeclared export bindings (`SyntaxError` at runtime). This commonly affected AWS SDK builds using `@smithy/credential-provider-imds`. (@dylan-conway) - Fixed: dynamic `import()` with import attributes (e.g. `{ with: { type: 'text' } }`) not applying the correct loader during bundling, which caused `--compile` builds to fail with `require_* is not defined` for `.html` files imported as text - Fixed: `bun build --compile` with HTML routes producing relative asset URLs (`./chunk-abc.js`) that broke when served from nested routes like `/foo/` — assets now use absolute root-relative URLs (`/chunk-abc.js`) - Fixed: Crash when resolving very long import paths (e.g. through tsconfig `baseUrl`, `paths` wildcards, or `node_modules` lookups) - Fixed: Dev server barrel optimizer incorrectly deferring `export *` target submodules, causing classes like `QueryClient` to become `undefined` and throwing `TypeError: Right-hand side of 'instanceof' is not an object` — affected packages like `@refinedev/core` with `@tanstack/react-query` ### CSS Parser - Fixed: CSS bundler incorrectly mapping logical border-radius properties (`border-start-start-radius`, `border-start-end-radius`, `border-end-start-radius`, `border-end-end-radius`) to only `border-top-left-radius`/`border-top-right-radius` when values contain `var()` references. All four logical properties now correctly resolve to their distinct physical counterparts. - Fixed: CSS `mask` shorthand parsing incorrectly dropping `geometry-box` values like `padding-box` and `content-box`, which could also cause rules with different geometry boxes to be incorrectly merged (@anthonybaldwin) - Fixed: `unicode-range` values in `@font-face` rules being mangled by the CSS processor (e.g., `U+0000-00FF` became `U0-0FF`), which caused browsers to silently ignore the entire `@font-face` rule and fonts to not load ### bun test - Fixed: `bun test` object diffs and `console.log` silently dropping properties with empty string keys (`""`) ### Bun Shell - Fixed: shell interpolation could crash given invalid input - Fixed: Bun's builtin `rm` in the shell returning exit code 0 instead of the correct non-zero exit code when a file doesn't exist and `.quiet()` or `.text()` is used. This also caused errors to never be thrown in those code paths. ### TypeScript types - Fixed: Missing `contentEncoding` property in the `S3Options` TypeScript type definition, which caused TypeScript errors and missing IDE autocompletion when using the `contentEncoding` option added in Bun v1.3.7 ### Runtime and CLI - Fixed: `bun run --filter` and `bun run --workspaces` failing when the `NODE` environment variable points to a non-existent file. Bun now validates that the path is an executable before using it, and falls back to searching `PATH` or creating its own node symlink. - Fixed: 100% CPU spin on Linux caused by the inotify file watcher re-parsing stale events in an infinite loop when a single `read()` returned more than 128 events - Fixed crashes when passing Proxy-wrapped arrays to built-in APIs (@sosukesuzuki) ### Thanks to 15 contributors! - [@alii](https://github.com/alii) - [@anthonybaldwin](https://github.com/anthonybaldwin) - [@baboon-king](https://github.com/baboon-king) - [@c-stoeckl](https://github.com/c-stoeckl) - [@cirospaciari](https://github.com/cirospaciari) - [@dylan-conway](https://github.com/dylan-conway) - [@gaowhen](https://github.com/gaowhen) - [@hona](https://github.com/hona) - [@igorkofman](https://github.com/igorkofman) - [@jarred-sumner](https://github.com/jarred-sumner) - [@km-anthropic](https://github.com/km-anthropic) - [@robobun](https://github.com/robobun) - [@sosukesuzuki](https://github.com/sosukesuzuki) - [@ssing2](https://github.com/ssing2) - [@whiteminds](https://github.com/whiteminds)

--- title: Bun v1.3.11 description: "Fixes 105 issues (addressing 307 👍). 4 MB smaller on Linux. x64 Bun.cron for OS-level cron jobs and expression parsing, Bun.sliceAnsi for ANSI/grapheme-aware string slicing, richer Bun.markdown list metadata; bun test --path-ignore-patterns; native Windows ARM64 .bin shim; dgram UDP fixed on macOS, fs.openSync numeric flags fixed on Windows (unbreaks tar@7), http2 WINDOW_UPDATE fix; bundler --bytecode/barrel/import-attribute fixes; CSS unicode-range/mask/border-radius fixes; Proxy-array crash fixes, CRLF injection fix, bun install hang fixes, and many Node.js compatibility improvements." date: "2026-03-18T04:16:10.096Z" author: jarred --- #### To install Bun {% codetabs %} ```sh#curl $ curl -fsSL https://bun.sh/install | bash ``` ```sh#npm $ npm install -g bun ``` ```sh#powershell $ powershell -c "irm bun.sh/install.ps1|iex" ``` ```sh#scoop $ scoop install 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 ``` ## 4 MB smaller on Linux x64 {% raw %}

In the next version of Bun

Bun gets 4 MB smaller on Linux x64 because we deleted CMake pic.twitter.com/HQPacwNO3O
— Bun (@bunjavascript) March 14, 2026

{% /raw %} ## `Bun.cron` — OS-level Cron Jobs and Expression Parsing Bun now includes a built-in `Bun.cron` API for registering OS-level cron jobs, parsing cron expressions, and removing scheduled jobs — all cross-platform. ### Register a cron job ```ts // Register a cron job (crontab on Linux, launchd on macOS, Task Scheduler on Windows) await Bun.cron("./worker.ts", "30 2 * * MON", "weekly-report"); ``` When the OS scheduler fires, Bun imports the script and calls `default.scheduled()`, following the [Cloudflare Workers Cron Triggers API](https://developers.cloudflare.com/workers/runtime-apis/handlers/scheduled/): ```ts#worker.ts // worker.ts export default { async scheduled(controller) { // controller.cron === "30 2 * * 1" // controller.scheduledTime === 1737340200000 await doWork(); }, }; ``` ### Parse cron expressions ```ts const next = Bun.cron.parse("*/15 * * * *"); // next quarter-hour const weekday = Bun.cron.parse("0 9 * * MON-FRI"); // next weekday at 9 AM UTC const yearly = Bun.cron.parse("@yearly"); // next January 1st // Chain calls to get a sequence const first = Bun.cron.parse("0 * * * *", from); const second = Bun.cron.parse("0 * * * *", first); ``` Returns a `Date` or `null` if no match exists within ~4 years (e.g. February 30th). ### Remove a job ```ts await Bun.cron.remove("weekly-report"); ``` ### Cron expression features - **Standard 5-field format** with `*`, `,`, `-`, `/` operators - **Named days and months**: `MON`–`SUN`, `JAN`–`DEC` (case-insensitive, full names supported) - **Nicknames**: `@yearly`, `@monthly`, `@weekly`, `@daily`, `@hourly` - **POSIX OR logic**: when both day-of-month and day-of-week are restricted, either matching fires the job - **Sunday as 7**: weekday field accepts both `0` and `7` ### Platform backends | Platform | Backend | Logs | | -------- | --------------- | ------------------------------------------- | | Linux | `crontab` | `journalctl -u cron` | | macOS | `launchd` plist | `/tmp/bun.cron..{stdout,stderr}.log` | | Windows | `schtasks` | Event Viewer → TaskScheduler | Re-registering with the same title overwrites the existing job in-place. ## `Bun.sliceAnsi` — ANSI & grapheme-aware string slicing  A new built-in that replaces both the [`slice-ansi`](https://www.npmjs.com/package/slice-ansi) and [`cli-truncate`](https://www.npmjs.com/package/cli-truncate) npm packages. `Bun.sliceAnsi` slices strings by terminal column width while preserving ANSI escape codes (SGR colors, OSC 8 hyperlinks) and respecting grapheme cluster boundaries (emoji, combining marks, flags). ```js // Plain slice (replaces slice-ansi) Bun.sliceAnsi("\x1b[31mhello\x1b[39m", 1, 4); // "\x1b[31mell\x1b[39m" // Truncation with ellipsis (replaces cli-truncate) Bun.sliceAnsi("unicorn", 0, 4, "…"); // "uni…" Bun.sliceAnsi("unicorn", -4, undefined, "…"); // "…orn" ``` The ellipsis is emitted **inside** active SGR styles (inherits color/bold) so truncated text stays visually consistent, but **outside** hyperlinks to avoid broken links. Negative indices are supported for slicing from the end. An optional `{ ambiguousIsNarrow }` option is available for controlling East Asian ambiguous width behavior, matching `Bun.stringWidth` and `Bun.wrapAnsi`. ### Performance Uses a three-tier dispatch strategy: - **SIMD ASCII fast path** — pure ASCII input is handled with a single SIMD scan and zero-copy when nothing is cut - **Single-pass streaming** — non-negative indices (the common case) walk the input once with stack-only allocation - **Two-pass for negative indices** — computes total width first, then emits ## `Bun.markdown.render()` now passes richer metadata to `listItem` and `list` callbacks The `listItem` callback in `Bun.markdown.render()` now receives `index`, `depth`, `ordered`, and `start` in its metadata object, and the `list` callback now includes `depth`. Previously, `listItem` only received `checked` (and only for task list items), making it impossible to know an item's position, nesting level, or parent list type without workarounds. This makes it straightforward to implement custom list markers like nested numbering schemes (`1.` / `a.` / `i.`) without regex post-processing: ```ts const result = Bun.markdown.render( "1. first\n 1. sub-a\n 2. sub-b\n2. second", { listItem: (children, { index, depth, ordered, start }) => { const n = (start ?? 1) + index; const marker = !ordered ? "-" : depth === 0 ? `${n}.` : `${String.fromCharCode(96 + n)}.`; return " ".repeat(depth) + marker + " " + children.trimEnd() + "\n"; }, list: (children) => "\n" + children, }, ); // 1. first // a. sub-a // b. sub-b // 2. second ``` The full `listItem` meta shape is now: | Property | Type | Description | | --------- | ---------------------- | ------------------------------------------------------- | | `index` | `number` | 0-based position within the parent list | | `depth` | `number` | Nesting level of the parent list (0 = top-level) | | `ordered` | `boolean` | Whether the parent list is ordered | | `start` | `number \| undefined` | Start number of the parent list (only set when ordered) | | `checked` | `boolean \| undefined` | Task list state (only set for `- [x]` / `- [ ]` items) | **Breaking change:** The `listItem` callback now **always** receives the meta object (previously it was only passed for task list items). `start` and `checked` are `undefined` when not applicable, keeping the object shape fixed for monomorphic inline caches. Meta objects use cached JSC structures internally, adding ~0.7ns per object overhead — effectively free. ## `--path-ignore-patterns` for `bun test`  You can now exclude files and directories from test discovery using glob patterns with the new `--path-ignore-patterns` flag or `test.pathIgnorePatterns` in `bunfig.toml`. This is useful when your project contains submodules, vendored code, or other directories with `*.test.ts` files that you don't want `bun test` to pick up. Matched directories are pruned during scanning, so their contents are never traversed — ignoring a large directory tree is efficient. ```toml # bunfig.toml [test] pathIgnorePatterns = [ "vendor/**", "submodules/**", "fixtures/**", "**/test-data/**" ] ``` Or via the command line: ```bash $ bun test --path-ignore-patterns 'vendor/**' --path-ignore-patterns 'fixtures/**' ``` Command-line `--path-ignore-patterns` flags override the `bunfig.toml` value entirely — the two are not merged. Thanks to @ctjlewis and @alii for the contribution! ## Fixed `dgram` UDP socket bugs on macOS  Fixed three bugs in UDP socket creation that caused `dgram` sockets to silently fail on macOS: - **`reusePort` now works on macOS**: The `reusePort: true` option was previously gated to Linux only. It now works on any platform that supports `SO_REUSEPORT`. - **Implicit bind-on-send works on macOS**: Calling `send()` on an unbound UDP socket should implicitly bind to `0.0.0.0` on a random port (matching Node.js behavior). Hardcoded Linux errno values (`92` instead of the `ENOPROTOOPT` macro) prevented IPv4 fallback paths from being taken on macOS, where `ENOPROTOOPT` is `42`. - **Socket fd leak on failure**: When `setsockopt` for reuse failed, the socket file descriptor was leaked and no diagnostic errno was propagated, producing generic "Failed to bind socket" errors. This affected real-world libraries like [`k-rpc`](https://github.com/mafintosh/k-rpc) (used by [`bittorrent-dht`](https://github.com/webtorrent/bittorrent-dht)) that rely on implicit binding behavior. ```js import dgram from "dgram"; const socket = dgram.createSocket("udp4"); // This now correctly auto-binds on macOS, matching Node.js behavior socket.send(Buffer.from("hello"), 0, 5, 41234, "127.0.0.1", (err) => { if (err) console.error("send error:", err); else console.log("sent successfully"); const addr = socket.address(); console.log("bound to:", addr); // Shows auto-assigned port socket.close(); }); ``` ## Native ARM64 shim for Windows `node_modules/.bin` binaries  The `bun_shim_impl.exe` used for `node_modules/.bin/*` on Windows was previously hardcoded to x86_64, meaning every package binary invocation on Windows ARM64 ran under x64 emulation. The shim is now compiled natively for aarch64 when building Bun for Windows ARM64, removing the emulation overhead. Thanks to @dylan-conway for the contribution! ## Bugfixes ### Node.js compatibility improvements - Fixed: An operator precedence bug in native readable streams caused `0 < MIN_BUFFER_SIZE` to be evaluated before the `??` operator, resulting in excessive memory allocation when processing stream chunks - Fixed: Custom `lookup` function in Node.js `http`/`https` client (e.g. via axios) breaking TLS certificate verification with `ERR_TLS_CERT_ALTNAME_INVALID` or `unknown certificate verification error`. When a custom DNS lookup resolved a hostname to an IP address, the original hostname was lost, causing TLS SNI and certificate verification to fail. - Fixed: `fs.openSync` and `fs.promises.open` throwing `EINVAL` on Windows when passed numeric flags from `fs.constants` (e.g. `O_CREAT | O_TRUNC | O_WRONLY`). The `fs.constants` values on Windows use native MSVC values which differ from Bun's internal representation, causing flags like `O_CREAT` to be silently dropped. This also fixes `UV_FS_O_FILEMAP` support, which unbreaks packages like `tar@7` (used by `npm`, `giget`, and others) that silently failed to extract files on Windows. (@Hona) - Fixed: `fs.stat` truncating sub-millisecond precision from `mtimeMs`, `atimeMs`, `ctimeMs`, and `birthtimeMs` properties, now returning fractional milliseconds matching Node.js behavior - Fixed: `fs.watch()` crash on Windows when a failed watch is retried on the same path - Fixed: a crash in `fs.watchFile` - Fixed: `node:fs` functions crashing with certain inputs - Fixed: crash (`cast causes pointer to be null`) on Windows when `fs.realpathSync` or `fs.readlink` encountered certain edge-case filesystem configurations like ramdisk volumes, substituted drives, or standalone executables in unusual locations - Fixed: `console.Console` returning `undefined` permanently after being accessed during a near-stack-overflow condition (@sosukesuzuki) - Fixed: `Buffer.compare` not properly validating `targetEnd` and `sourceEnd` offset bounds, where certain combinations of start/end values could bypass range checks instead of throwing `ERR_OUT_OF_RANGE` as Node.js does - Fixed: rare crash in `Buffer.indexOf`, `Buffer.lastIndexOf`, and `Buffer.includes` - Fixed: buffer overflow in path-handling code - Fixed: `process.off("SIGxxx", handler)` removing one of multiple signal listeners would incorrectly uninstall the OS signal handler, causing remaining listeners to stop receiving signals - Fixed: `execFileSync` and `execSync` errors containing a self-referencing cycle (`err.error === err`) that caused `JSON.stringify(err)` to throw - Fixed: `spawnSync` could accidentally drain the global microtask queue, executing user JavaScript during what should be a synchronous, blocking call. - Fixed: missing BoringSSL error clearing in `crypto.createPrivateKey()` - Fixed: Crash in `crypto.Hash` `update()`/`digest()` caused by missing `this` validation, a GC hazard on input strings during encoding conversion, and reading from detached buffers. Now properly throws `ERR_INVALID_THIS` and `ERR_INVALID_STATE` instead of crashing. - Fixed: crashs when calling native crypto/stream prototype methods (like `Hmac.digest()`, `DiffieHellmanGroup.verifyError`) with an invalid `this` value — now correctly throws `ERR_INVALID_THIS` instead of crashing - Fixed: `X509Certificate.prototype` was `undefined`, which prevented subclassing with `class Foo extends X509Certificate {}` (@sosukesuzuki) - Fixed: `getPeerCertificate()` returning `undefined` instead of `{}` when no peer certificate is available, which caused `checkServerIdentity()` to crash with `TypeError: Cannot destructure property 'subject' from null or undefined value` during TLS handshakes — most notably when connecting to MongoDB Atlas clusters - Fixed: hypothetical out of bounds read/write in native zlib `write()`/`writeSync()` where user-controlled offset and length parameters were not properly validated in production builds. These now correctly throw `ERR_OUT_OF_RANGE`, `ERR_INVALID_ARG_TYPE`, and other appropriate errors. - Fixed: `dgram.createSocket()` incorrectly set `SO_REUSEADDR` on all UDP sockets, allowing multiple processes to silently bind to the same port without throwing `EADDRINUSE` — diverging from Node.js behavior. `SO_REUSEADDR` is now only applied when `reuseAddr: true` is explicitly passed. - Fixed: a latent GC safety issue in `node:vm` modules where a garbage collection cycle during object construction could lead to a crash (@sosukesuzuki) - Fixed: `structuredClone()` throwing `DataCloneError` on objects created via `napi_create_object`, matching Node.js behavior (@dylan-conway) - Fixed: `node:http2` client streams stalling after receiving 65,535 bytes when using `setLocalWindowSize()` — the method updated the internal connection window size but never sent a `WINDOW_UPDATE` frame to the peer, causing the server to stop sending data once the default window was exhausted - Fixed: `node:http2` `getPackedSettings`, `getUnpackedSettings`, and `getDefaultSettings` now match Node.js behavior, including support for `enableConnectProtocol`, `customSettings`, correct `enablePush` default, and proper `ERR_HTTP2_INVALID_SETTING_VALUE` error codes (@cirospaciari) - Fixed: crash that could occur on exit when using NAPI native addon modules (such as `skia-canvas`) on Windows - Fixed: bug in libuv on Windows that could cause pipe data loss when reading from subprocess pipes ### Bun APIs - Fixed PgBouncer incompatibility with `sql.prepare(false)` queries - Fixed: `Bun.file().text()` and similar async read methods not keeping event loop alive when an error errors - Fixed: Incorrect `Bun.file()` async read error paths on Windows - Fixed: `Bun.file().stat()` and `Bun.file().delete()` corrupting file paths containing non-ASCII UTF-8 characters (e.g., German umlauts, Japanese characters, emoji), causing `ENOENT` errors due to double-encoding - Fixed: `Bun.stdin.stream()` and `Bun.stdin.text()` returning empty on Linux after calling `Bun.stdin.exists()` or accessing `Bun.stdin.size` - Fixed: `Bun.JSONL.parseChunk(input, start, end)` now honors `start`/`end` offsets when `input` is a string. - Fixed: `S3File.slice(0, N).stream()` ignoring the slice range and downloading the entire file instead of only the requested byte range - Fixed: `bun:sql` panicking with "integer does not fit in destination type" when a PostgreSQL query exceeded the 65,535 parameter limit (e.g. batch inserting 7,000 rows × 10 columns). Now throws a descriptive `PostgresError` with code `ERR_POSTGRES_TOO_MANY_PARAMETERS` and a hint to reduce batch size - Fixed: Valkey RESP protocol parser no longer crashes with a stack overflow on deeply nested server responses by enforcing a maximum nesting depth of 128 for aggregate types (@dylan-conway) - Fixed: `Bun.Transpiler` ignoring `experimentalDecorators: true` and `emitDecoratorMetadata: true` from tsconfig, always emitting TC39-style decorators instead of legacy TypeScript decorators. This broke frameworks like Angular that rely on legacy decorator calling conventions in JIT mode. - Fixed: `Bun.Transpiler.scanImports()` and `Bun.Transpiler.scan()` ignoring the `trimUnusedImports` option — unused imports were only being trimmed by `transformSync()` - Fixed: memory leak in `Bun.Transpiler` when using a custom `tsconfig` with async `transform()` calls. After the first `await transpiler.transform()`, subsequent calls could read freed memory or double-free the tsconfig pointer, potentially causing crashes. - Fixed: `emitDecoratorMetadata: true` in tsconfig.json without `experimentalDecorators: true` incorrectly used TC39 standard decorators instead of legacy decorator semantics, causing NestJS, TypeORM, Angular, and other legacy-decorator frameworks to crash with `descriptor.value` undefined - Fixed: Breakpoints landing at wrong line numbers when debugging files over 50KB in VSCode's debug terminal (`BUN_INSPECT` env var). The runtime transpiler cache was not being disabled when the debugger was activated via the `BUN_INSPECT` environment variable (as opposed to `--inspect` CLI flags), causing cached output without inline source maps to be used. (@alii) - Fixed: HTML-referenced assets (favicons, images, etc.) returning 404 when served with `Bun.serve()` because they were missing from the bundle manifest's `files` array despite being correctly emitted to disk - Fixed `ReadableStream` with `type: "direct"` incorrectly calling the user's `cancel` callback on normal stream completion - Fixed: Empty string arguments in Bun shell - Fixed: DoS in `Bun.stringWidth` - Fixed: `Bun.stringWidth` grapheme bug: ANSI escape bytes were incorrectly included in grapheme break tracking ### Web APIs - Fixed: incorrect value in `WebSocket.prototype.protocol` in certain cases - Fixed: `ws.ping()` and `ws.pong()` called without arguments incorrectly sent non-empty payloads instead of empty control frames, causing disconnections with strict WebSocket servers (e.g. Binance) that validate pong payloads match ping payloads (@gaowhen) - Fixed: WebSocket client now validates the `Sec-WebSocket-Accept` header value during the upgrade handshake per RFC 6455 §4.2.2, rejecting connections where the server returns a stale or mismatched response - Fixed: `Request.formData()` truncating small binary files with null bytes - Fixed: a crash when calling `fetch()` using a very large number of headers - Fixed: crash in fetch with TLS proxies in certain cases - Fixed: Edgecase with pipelined HTTP requests with no headers - Fixed: HTTP header value incorrect stripping for certain cases - Hardened Bun's HTTP server against malformed chunked transfer requests. Thanks to @sim1222 for reporting issues. - Fixed: CRLF injection vulnerability in `ServerResponse.prototype.writeEarlyHints` where header names and values were written to the socket without validation, allowing HTTP response splitting attacks - Fixed: WebSocket connections dropping over proxy tunnels with bidirectional traffic ### bun install - Fixed: `bun install` hanging indefinitely or silently skipping processing when a security scanner is enabled and the project has more than ~790 packages. The package list is now sent to the scanner subprocess via an IPC pipe instead of command-line arguments, avoiding OS argument length limits - Fixed: `bun install` hanging indefinitely (~300 seconds per dependency) when using an HTTP proxy (`http_proxy`/`https_proxy`) with cached packages that return `304 Not Modified` through a CONNECT tunnel (@WhiteMinds) - Fixed: Non-deterministic `bun install` bug where transitive peer dependencies were left unresolved when all manifest loads were synchronous (e.g., warm cache with valid `Cache-Control: max-age`), causing missing peer dependency symlinks with `--linker=isolated` (@dylan-conway) - Fixed: `.npmrc` auth token matching only comparing hostnames - Fixed: `bun install` silently exiting with code 1 when the security scanner encounters an error, making failures impossible to debug (especially in CI). All error paths now print descriptive messages to stderr. - Fixed: `bun install` now shows an accurate error message when a `file:` dependency path is missing (e.g., due to a stale lockfile), instead of the misleading "Bun could not find a package.json file to install from" message. The new error clearly identifies the dependency and the exact path that was not found. - Fixed: `bun update -i` select all ('A' key) now correctly updates packages instead of showing "No packages selected for update" - Fixed: `bun pack` and `bun publish` using stale `version` and `name` from `package.json` when lifecycle scripts (`prepublishOnly`, `prepack`, `prepare`) modify them during execution. Previously, the tarball filename and publish registry metadata would use the original values captured before scripts ran. (@dylan-conway) - Fixed: `bun bun.lockb | head` no longer prints an internal `BrokenPipe` error message instead of exiting silently ### JavaScript bundler - Fixed: `bun build --compile --bytecode --format=esm` crashing at runtime with "Cannot find module" errors when barrel-optimized packages (those with `"sideEffects": false`) had unused re-exports recorded as external dependencies in bytecode ModuleInfo (@Jarred-Sumner) - Fixed: `import Bun from 'bun'` returning `undefined` when bundled with `--bytecode` flag. The CJS lowering pass was incorrectly generating `globalThis.Bun.default` instead of `globalThis.Bun` for default imports. - Fixed: Bundler dropping exports when barrel files with `sideEffects: false` re-export namespace imports (`import * as X from './mod'; export { X }`), causing `ReferenceError` for the re-exported bindings at runtime - Fixed: Bundler barrel optimization incorrectly dropped exports needed by dynamic `import()` when the same barrel was also referenced by a static named import, producing invalid JS with undeclared export bindings (`SyntaxError` at runtime). This commonly affected AWS SDK builds using `@smithy/credential-provider-imds`. (@dylan-conway) - Fixed: dynamic `import()` with import attributes (e.g. `{ with: { type: 'text' } }`) not applying the correct loader during bundling, which caused `--compile` builds to fail with `require_* is not defined` for `.html` files imported as text - Fixed: `bun build --compile` with HTML routes producing relative asset URLs (`./chunk-abc.js`) that broke when served from nested routes like `/foo/` — assets now use absolute root-relative URLs (`/chunk-abc.js`) - Fixed: Crash when resolving very long import paths (e.g. through tsconfig `baseUrl`, `paths` wildcards, or `node_modules` lookups) - Fixed: Dev server barrel optimizer incorrectly deferring `export *` target submodules, causing classes like `QueryClient` to become `undefined` and throwing `TypeError: Right-hand side of 'instanceof' is not an object` — affected packages like `@refinedev/core` with `@tanstack/react-query` ### CSS Parser - Fixed: CSS bundler incorrectly mapping logical border-radius properties (`border-start-start-radius`, `border-start-end-radius`, `border-end-start-radius`, `border-end-end-radius`) to only `border-top-left-radius`/`border-top-right-radius` when values contain `var()` references. All four logical properties now correctly resolve to their distinct physical counterparts. - Fixed: CSS `mask` shorthand parsing incorrectly dropping `geometry-box` values like `padding-box` and `content-box`, which could also cause rules with different geometry boxes to be incorrectly merged (@anthonybaldwin) - Fixed: `unicode-range` values in `@font-face` rules being mangled by the CSS processor (e.g., `U+0000-00FF` became `U0-0FF`), which caused browsers to silently ignore the entire `@font-face` rule and fonts to not load ### bun test - Fixed: `bun test` object diffs and `console.log` silently dropping properties with empty string keys (`""`) ### Bun Shell - Fixed: shell interpolation could crash given invalid input - Fixed: Bun's builtin `rm` in the shell returning exit code 0 instead of the correct non-zero exit code when a file doesn't exist and `.quiet()` or `.text()` is used. This also caused errors to never be thrown in those code paths. ### TypeScript types - Fixed: Missing `contentEncoding` property in the `S3Options` TypeScript type definition, which caused TypeScript errors and missing IDE autocompletion when using the `contentEncoding` option added in Bun v1.3.7 ### Runtime and CLI - Fixed: `bun run --filter` and `bun run --workspaces` failing when the `NODE` environment variable points to a non-existent file. Bun now validates that the path is an executable before using it, and falls back to searching `PATH` or creating its own node symlink. - Fixed: 100% CPU spin on Linux caused by the inotify file watcher re-parsing stale events in an infinite loop when a single `read()` returned more than 128 events - Fixed crashes when passing Proxy-wrapped arrays to built-in APIs (@sosukesuzuki) ### Thanks to 15 contributors! - [@alii](https://github.com/alii) - [@anthonybaldwin](https://github.com/anthonybaldwin) - [@baboon-king](https://github.com/baboon-king) - [@c-stoeckl](https://github.com/c-stoeckl) - [@cirospaciari](https://github.com/cirospaciari) - [@dylan-conway](https://github.com/dylan-conway) - [@gaowhen](https://github.com/gaowhen) - [@hona](https://github.com/hona) - [@igorkofman](https://github.com/igorkofman) - [@jarred-sumner](https://github.com/jarred-sumner) - [@km-anthropic](https://github.com/km-anthropic) - [@robobun](https://github.com/robobun) - [@sosukesuzuki](https://github.com/sosukesuzuki) - [@ssing2](https://github.com/ssing2) - [@whiteminds](https://github.com/whiteminds)