Why

Vite doesn't support polyfill detection by default. You can use @vitejs/plugin-legacy with modernPolyfills but it is Babel-based and can be slow.

Rolldown (or rather oxc) currently doesn't support polyfill detection at all. This plugin uses swc to detect and include polyfills based on the usage and target browsers.

Plugin assumes modern browsers so it doesn't include regenerator-runtime. If you need to support legacy browsers you should use @vitejs/plugin-legacy instead.

Usage

import { defineConfig } from "vite";
import polyfillDetection from "@nulladdict/vite-plugin-polyfill-detection";

export default defineConfig({
  plugins: [
    polyfillDetection({
      targets: ["chrome >= 111", "edge >= 111", "firefox >= 114", "safari >= 16.4"],
    }),
  ],
});

Options

targets

• Type: string | Array<string> | Record<string, string>
• Required

Specifies which browsers to polyfill for. Passed as targets to @swc/core to determine which polyfills are needed based on actual usage in your code. The query is browserslist-compatible with some limitations.