@gas-plugin/unplugin

A universal bundler plugin for Google Apps Script (GAS) projects. Works with Vite, Rollup, Rolldown, webpack, esbuild, and Bun.

What It Does

Google Apps Script requires plain top-level function declarations — no export keywords, no ES module syntax. This plugin bridges the gap between modern bundler output and what GAS expects:

• Strips export keywords from function/class/variable declarations
• Removes export { ... } blocks generated by bundlers
• Prevents tree-shaking of GAS entry points (e.g., onOpen, doGet)
• Copies appsscript.json manifest to the output directory
• Copies additional files (HTML, JSON, etc.) via glob patterns

Install

# npm
npm install -D @gas-plugin/unplugin

# yarn
yarn add -D @gas-plugin/unplugin

# pnpm
pnpm add -D @gas-plugin/unplugin

Usage

Vite

// vite.config.ts
import gasPlugin from "@gas-plugin/unplugin/vite";
import { defineConfig } from "vite";

export default defineConfig({
  plugins: [gasPlugin()],
  build: {
    lib: {
      entry: "src/main.ts",
      formats: ["es"],
      fileName: () => "Code.js",
    },
  },
});

Rollup

// rollup.config.js
import gasPlugin from "@gas-plugin/unplugin/rollup";

export default {
  input: "src/main.ts",
  output: { dir: "dist", format: "es" },
  plugins: [gasPlugin()],
};

webpack

// webpack.config.js
const gasPlugin = require("@gas-plugin/unplugin/webpack").default;

module.exports = {
  entry: "./src/main.ts",
  output: { path: __dirname + "/dist" },
  plugins: [gasPlugin()],
};

esbuild

import gasPlugin from "@gas-plugin/unplugin/esbuild";
import { build } from "esbuild";

await build({
  entryPoints: ["src/main.ts"],
  outdir: "dist",
  bundle: true,
  format: "esm",
  plugins: [gasPlugin()],
});

Rolldown

// rolldown.config.mjs
import gasPlugin from "@gas-plugin/unplugin/rolldown";

export default {
  input: "src/main.ts",
  output: { dir: "dist", format: "es" },
  plugins: [gasPlugin()],
};

Bun

import gasPlugin from "@gas-plugin/unplugin/bun";

await Bun.build({
  entrypoints: ["src/main.ts"],
  outdir: "dist",
  plugins: [gasPlugin()],
});

Options

interface GasPluginOptions {
  /**
   * Path to appsscript.json manifest file.
   * Resolved relative to the project root.
   * @default "appsscript.json"
   */
  manifest?: string;

  /**
   * Glob patterns for additional files to copy flat to the output directory.
   * Files are copied without subdirectory structure (basename only).
   * Duplicate basenames trigger a warning; the first match wins.
   * @default []
   */
  include?: string[];

  /**
   * Function names to explicitly protect from tree-shaking.
   * These functions will be kept as top-level declarations in the output,
   * even if they are not exported from the entry point.
   * @default []
   */
  globals?: string[];

  /**
   * When true (default), exported functions are automatically added to the
   * tree-shake protection list. When false, only functions explicitly listed
   * in `globals` are protected.
   * @default true
   */
  autoGlobals?: boolean;
}

Examples

Basic GAS Project

// vite.config.ts
import gasPlugin from "@gas-plugin/unplugin/vite";
import { defineConfig } from "vite";

export default defineConfig({
  plugins: [gasPlugin()],
  build: {
    lib: {
      entry: "src/main.ts",
      formats: ["es"],
      fileName: () => "Code.js",
    },
  },
});

GAS Web App with HTML

// vite.config.ts
import gasPlugin from "@gas-plugin/unplugin/vite";
import { defineConfig } from "vite";

export default defineConfig({
  plugins: [
    gasPlugin({
      include: ["src/**/*.html"],
      globals: ["getData", "saveData"],
    }),
  ],
  build: {
    lib: {
      entry: "src/main.ts",
      formats: ["es"],
      fileName: () => "Code.js",
    },
  },
});

How It Works

1. Transform phase: Detects exported function declarations and injects tree-shake protection markers (globalThis.__gas_keep__) to prevent bundlers from removing GAS entry points.

2. Post-process phase: After bundling, strips all export keywords and export { ... } blocks, removes the tree-shake protection markers, and normalizes trailing newlines.

3. File copy phase: Copies appsscript.json and any files matching include patterns to the output directory.

Compatibility

| Bundler | Version | | -------- | -------------- | | Vite | >= 5.0.0 | | Rollup | >= 4.0.0 | | Rolldown | >= 1.0.0-rc.1 | | webpack | >= 5.0.0 | | esbuild | >= 0.17.0 | | Bun | latest |

Node.js: >= 20

License

MIT