A small plugin to insert an arbitrary string at the beginning of generated content. Inspired by esbuild banner option.

bun add -D bun-banner-plugin

build.ts:

import { bannerPlugin } from "bun-banner-plugin";

await Bun.build({
  entrypoints: ["src/index.ts"],
  outdir: "dist",
  target: "node",
  minify: true,
  plugins: [
    bannerPlugin({
      // Add banners to json files
      jsonc: ["// This is a jsonc file", "// Hello, jsonc!"],

      // Add a shebang to the top of `.ts`, `.tsx`, `.js`, `.jsx` files
      "ts|tsx|js|jsx": "#!/usr/bin/env node",
    }),
  ],
});

Suppose you have the following src/index.ts.

console.log("Hello, world!");

Now, using the build.ts I wrote in Usage, run bun run build.ts, the following will be output:

#!/usr/bin/env node
console.log("Hello, world!");

• The key is a regular expression that matches the file extension.
  • The given key is interpreted as a regular expression, so you need to escape special characters.
  • For example:
    • If the key is json, it will interpreted as /.(json)$/. It will match .json files.
    • If the key is ts|tsx|js|jsx, it will iterpreted as /.(ts|tsx|js|jsx)$/. It will match .ts, .tsx, .js, .jsx files.
• The value is the string to be inserted at the beginning of the file.

  • If the value is an array, the strings in the array will be joined with a newline character.

  • If the value is a string, it will be inserted as is.

  • For example, If the value is ["// This is a jsonc file", "// Hello, jsonc!"], it will be inserted as follows:

    // This is a jsonc file
    // Hello, jsonc!
    {
      "foo": "bar",
    }

1. Update version in package.json
2. commit with tag vX.X.X
3. push to GitHub