Setting the file. One moment.
Subchapter 5.1
references/FROM_BUN.mdMarkdown4 KBView on GitHub
Most Bun projects are ordinary package.json + TypeScript projects, which Deno
runs directly: same npm dependencies, TypeScript with no build step, comparable
built-in toolchain.
Bun is the one migration here involving real code changes, because Bun.*
API calls have to be translated. Anything on Web and Node APIs moves unchanged.
| Bun | Deno |
|---|---|
bun install | deno install |
bun add <pkg> | deno add <pkg> |
bun add -d <pkg> | deno add -D <pkg> |
bun remove <pkg> | deno remove <pkg> |
bun run <script> | deno task <script> |
bun <file> | deno <file> |
bunx <pkg> | dx <pkg> |
bun test | deno test |
bun build --compile | deno compile |
bun outdated | deno outdated |
bun audit | deno audit |
bun why <pkg> | deno why <pkg> |
bun ci | deno ci |
bun --watch <file> | deno watch <file> |
Both take a fetch-style handler receiving a Request and returning a
Response, but the shapes differ: Bun.serve takes one options object with a
fetch property; Deno.serve takes the handler as a separate argument. Passing
fetch in the options object to Deno.serve throws.
// Bun
Bun.serve({
port: 3000,
fetch(req) {
return new Response("hi");
},
});
// Deno
Deno.serve({ port: 3000 }, (req) => new Response("hi"));Deno.serve(handler) with no options is also valid and defaults to port 8000.
Deno ships the synchronous node:sqlite built-in — same prepare/run/get/all
workflow, different class names.
import { DatabaseSync } from "node:sqlite";
const db = new DatabaseSync(":memory:");
db.exec("CREATE TABLE t (a TEXT)");
const stmt = db.prepare("INSERT INTO t VALUES (?)");
stmt.run("x");Bun.file() returns a lazy reference; Deno reads eagerly or opens a handle:
const text = await Deno.readTextFile("./data.json"); // whole file
const bytes = await Deno.readFile("./image.png");
using file = await Deno.open("./big.log"); // streamingDeno.open returns a handle with a .readable stream, the closest analogue to
Bun.file().stream().
deno test uses Deno.test() but also understands node:test. For a suite
already using describe/it, node:test plus node:assert is the smaller
diff:
import { describe, it } from "node:test";
import assert from "node:assert";
describe("math", () => {
it("adds", () => assert.equal(1 + 1, 2));
});For new tests, Deno.test() with jsr:@std/assert is the idiomatic form.
For template-literal shell syntax add jsr:@david/dax; for subprocess control
without a dependency use Deno.Command:
const { stdout } = await new Deno.Command("git", {
args: ["rev-parse", "HEAD"],
}).output();Note that subprocesses need --allow-run.
| Bun | Deno |
|---|---|
Bun.env | Deno.env.get() (needs --allow-env) |
Bun.password | node:crypto, or a JSR/npm hashing package |
Bun.hash | node:crypto |
Bun.write | Deno.writeTextFile / Deno.writeFile |
Bun.spawn | Deno.Command |
bunfig.toml has no counterpart; its contents move into deno.json (tasks,
formatter and linter settings) or tsconfig.json (compiler options). See the
deno skill.
with { type: "macro" }) — no counterpart.deno compile for a standalone binary.The difference that surfaces first: Bun grants unrestricted access, Deno
nothing. Use -A while confirming the program works, then narrow.