Bun v1.2.19

{
  "dependencies": {
    "react": "18.2.0"
  },
  "devDependencies": {
    "react": "18.3.0"
  },
  "peerDependencies": {
    "react": "18.2.1"
  }
}

# ./.npmrc
save-exact=true

// See the dependency path to a package
$ bun why react

react@18.2.0
  └─ my-app@1.0.0 (requires ^18.0.0)

// Use glob patterns to query multiple packages
$ bun why "@types/*"

@types/react@18.2.15
  └─ dev my-app@1.0.0 (requires ^18.0.0)

@types/react-dom@18.2.7
  └─ dev my-app@1.0.0 (requires ^18.0.0)

// package.json
{
  "name": "my-monorepo",
  "workspaces": ["packages/*"],

  // `catalog` and `catalogs` can now be defined at the top-level
  // instead of being nested inside the `workspaces` object.
  "catalog": {
    "react": "18.2.0"
  },
  "catalogs": {
    "testing": {
      "@testing-library/react": "16.0.0",
    }
  }
}

import { test, expect } from "bun:test";

const testCases = [
  { user: { name: "Alice" }, a: 1, b: 2, expected: 3 },
  { user: { name: "Bob" }, a: 5, b: 5, expected: 10 },
];

// The test runner will generate titles like:
// ✓ Add 1 and 2 for Alice
// ✓ Add 5 and 5 for Bob
test.each(testCases)("Add $a and $b for $user.name", ({ a, b, expected }) => {
  expect(a + b).toBe(expected);
});

# bun.toml

[test]
# You can use a single pattern as a string
# coveragePathIgnorePatterns = "**/__tests__/**"

# Or an array of glob patterns
coveragePathIgnorePatterns = [
  "**/__tests__/**",
  "**/test-fixtures.ts",
]

- // Bun Snapshot v1, https://goo.gl/fbAQLP
+ // Bun Snapshot v1, https://bun.net.cn/docs/test/snapshots

import { SQL } from "bun:sql";

const db = new SQL("postgres://user:pass@host:port/db");

// Bun automatically pipelines these queries,
// sending them to the server without waiting for each response individually.
const queries = [];
for (let i = 0; i < 100; i++) {
  // .execute() is used for fire-and-forget queries
  queries.push(db`SELECT ${i}`.execute());
}

// Await all results
const results = await Promise.all(queries);
console.log(results.length); // 100

await db.end();

# To use, set your DATABASE_URL and run Bun with the flag.
export DATABASE_URL="postgres://user:pass@host:port/db"

# Bun will connect to PostgreSQL before index.js is executed.
bun --sql-preconnect index.js

// index.js
const nested = {
  a: {
    b: {
      c: {
        d: "I am deeply nested",
      },
    },
  },
};
console.log(nested);

// By default, the output is truncated to a depth of 2.
// $ bun run index.js
// { a: { b: [Object] } }

// Run with `--console-depth=4` to see the full object.
// $ bun --console-depth=4 run index.js
// { a: { b: { c: { d: 'I am deeply nested' } } } }

// Alternatively, configure this in `bunfig.toml`:
// [run]
// console.depth = 4

[run]
console.depth = 4

/*
  This is a very, very, very, very, very, very, very, very,
  very, very, very, very, very, very, very, very, very,
  very, very, very, very, very, very, very, very, very,
  very, very, very, very, very, very, very, very, very,
  very, very, very, very, very, very, very, very, very,
  very, very, very, very, very, very, very, very, very,
  very, very, very, very, very, very, very, very, very,
  ... and so on for many many many thousands of lines ...
  very, very, very, very, very, very, very, very, very,
  very, very, very, very, very, very, very, very, long
  multiline comment.

  Bun's lexer now uses SIMD instructions to skip over
  this block of text much faster than before.
*/
console.log("This file now parses much faster!");

// input.js
function test() {
  return "foo";

  // This code is unreachable and will be removed.
  try {
    return "bar";
  } catch (e) {
    console.log(e);
  }
}

// bun build --minify ./input.js
// Before:
function test() {
  return "foo";
  try {
    return "bar";
  } catch (e) {
    console.log(e);
  }
}

// After:
function test() {
  return "foo";
}

Symbol.for("this will be removed");
const a = Symbol.for("this will be kept");
console.log(a);

var o=Symbol.for("this will be kept");console.log(o);

import vm from "node:vm";

const contextified = vm.createContext({});
// false: globalThis in child context is a different object than the parent's reference to the context
console.log(vm.runInContext("globalThis", contextified) === contextified);

const notContextified = vm.createContext(vm.constants.DONT_CONTEXTIFY);
// true: parent and child context have the same object
console.log(vm.runInContext("globalThis", notContextified) === notContextified);

import { networkInterfaces } from "os";

const interfaces = networkInterfaces();

for (const name of Object.keys(interfaces)) {
  for (const net of interfaces[name]) {
    // For IPv6, the `scopeid` property is now correctly named.
    if (net.family === "IPv6") {
      console.log(net.scopeid);
      // => 0 (or another number)

      console.log(net.scope_id);
      // => undefined
    }
  }
}

console.log(process.features.typescript);
// "transform"

console.log(process.features.require_module);
// true

console.log(process.features.openssl_is_boringssl);
// true

import { globSync } from "node:fs";
import { mkdirSync, writeFileSync } from "node:fs";

// Create some dummy files for demonstration
mkdirSync("a", { recursive: true });
mkdirSync("b", { recursive: true });
writeFileSync("a/file.js", "");
writeFileSync("a/file.ts", "");
writeFileSync("a/style.css", "");
writeFileSync("b/component.js", "");

// Match all .js and .ts files, but exclude anything in the 'b' directory.
const files = globSync(["**/*.js", "**/*.ts"], {
  ignore: ["b/**"], // or `exclude`
});

console.log(files.sort());
// => ["a/file.js", "a/file.ts"]

import { SourceMap } from "node:module";

const payload = {
  version: 3,
  file: "output.js",
  sources: ["input.js"],
  sourcesContent: ["() => {}"],
  names: ["add"],
  mappings: "AAAA,SAASA,GAAG",
};

const map = new SourceMap(payload);

// The payload getter returns the object used to construct the SourceMap
console.log(map.payload);
// { version: 3, file: 'output.js', ... }

// Find the original source location for a given generated location
const entry = map.findEntry(0, 9);
console.log(entry);
// {
//   generatedLine: 0,
//   generatedColumn: 9,
//   originalLine: 0,
//   originalColumn: 9,
//   originalSource: 'input.js',
//   name: 'add'
// }