Chrome Extension Multiple Entry Points

The Problem

Chrome extensions need multiple entry points (background, content, popup), but modern bundlers create shared chunks that Chrome cannot load across isolated execution contexts.

The Solution

Use a separate Vite config file for each entry point. Each build produces a self-contained IIFE file with no shared chunks.

Project Structure

my-extension/
├── src/
│   ├── background/background.ts
│   ├── content/content.ts
│   ├── popup/
│   │   ├── popup.ts
│   │   ├── popup.html
│   │   └── popup.css
│   └── manifest.json
├── vite.background.config.ts
├── vite.content.config.ts
├── vite.popup.config.ts
└── package.json

package.json Scripts

{
  "scripts": {
    "build": "shx rm -rf dist && shx mkdir -p dist && pnpm run build:all && pnpm run copy:assets",
    "build:all": "pnpm run build:background && pnpm run build:content && pnpm run build:popup",
    "build:background": "vite build --config vite.background.config.ts",
    "build:content": "vite build --config vite.content.config.ts",
    "build:popup": "vite build --config vite.popup.config.ts",
    "copy:assets": "shx cp src/manifest.json src/popup/popup.html src/popup/popup.css dist/",
    "dev": "pnpm run build && pnpm run build --watch"
  },
  "devDependencies": {
    "@types/chrome": "^0.0.323",
    "typescript": "^5.8.3",
    "vite": "^6.3.5",
    "shx": "^0.3.4"
  }
}

Vite Config Pattern

Each config follows the same pattern — only the input file and output filename differ:

import { defineConfig } from "vite"
import { resolve } from "path"

export default defineConfig({
  build: {
    emptyOutDir: false,
    rollupOptions: {
      input: resolve(__dirname, "src/background/background.ts"),
      output: {
        entryFileNames: "background.js",
        dir: "dist",
        format: "iife",
        inlineDynamicImports: true,
      },
    },
    target: "es2020",
  },
  define: {
    'process.env': {},
    'global': 'globalThis'
  },
})

Key Rules

• Use format: "iife" — not ES modules
• Set inlineDynamicImports: true — no shared chunks
• Use emptyOutDir: false — each build appends to dist/, not overwrites
• Use shx for cross-platform copy/rm commands
• Accept that dependencies are duplicated across bundles — that is intentional