Bun v0.5.9

Bun v0.5.9 introduces watch mode using bun --watch, adds support for tarball dependencies in bun install, and fixes lots of bugs to improve stability and compatibility.

curl -fsSL https://bun.sh/install | bash

npm install -g bun

brew tap oven-sh/bun

brew install bun

docker pull oven/bun

docker run --rm --init --ulimit memlock=-1:-1 oven/bun

To upgrade Bun:

bun upgrade

Watch mode

Bun now supports watch mode using bun --watch, which auto-restarts your application when you make a change to your files. This is useful in development to quickly see changes you've made to your code. It's a builtin replacement for nodemon that is noticeably faster.

Run a file with bun --watch

Run tests with bun test --watch

Bun still supports bun --hot, which attempts to reload your application code without restarting the whole process. This is particularly useful when developing a server with Bun.serve, especially one long-lived connections like WebSockets. But in most cases --watch is a better general purpose tool.

Tarball dependencies

You can now use tarball dependencies in your package.json. Bun will download and install the package from the specified tarball URL, rather than from npm (or whichever package registry you have configured).

{
  "dependencies": {
    "zod": "https://registry.npmjs.org/zod/-/zod-3.21.4.tgz"
  }
}

Use tarball URLs to include a dependency that is not in a registry or privately hosted.

Squashed bugs

We fixed a lot of bugs this release, here are a few interesting highlights.

• The url.origin property is to "null" when the protocol is non-HTTP.

test("url.origin is null when protocol is non-http", () => {
  expect(new URL("https://example.com")).toHaveProperty(
    "origin",
    "https://example.com",
  );
  expect(new URL("file://path/to/file")).toHaveProperty("origin", "null");
  expect(new URL("about:blank")).toHaveProperty("origin", "null");
});

• Set-Cookie headers are no longer de-duplicated.

test("headers can handle duplicate set-cookie headers", () => {
  const headers = new Headers([["Set-Cookie", "foo=bar"]]);
  headers.append("set-Cookie", "foo=baz");
  expect([...headers]).toEqual([
    ["set-cookie", "foo=bar"],
    ["set-cookie", "foo=baz"],
  ]);
});

• An invalid Date now console.log() as "Invalid Date".

test("invalid date inspects as 'Invalid Date'", () => {
  expect(Bun.inspect(new Date("hello world"))).toBe("Invalid Date");
});

• Node.js' util.isError() function now works for objects that are "Error-like".

test("util.isError() works for non-native errors", () => {
  const actual = util.isError({ name: "Error", message: "an error occurred" });
  expect(actual).toBe(true);
});

• We also improved the Error messages when you import a Node.js module that has not been implemented yet in Bun, like node:http2 and node:vm.

Looking ahead

A new JavaScript bundler is coming, including builtin support for server components.

Changelog

Contributors

And finally, thank you to all the contributors from the community that helped improve Bun this release: @jq170727, @JacksonKearl, @johnnyreilly, @gaurishhs, @Fire-The-Fox, @bnzone, @JokerQyou, @andres039, @Validark, @adrien-zinger, @jakeboone02