gem-hunter

Automatically add /* #__PURE__ */ annotations before definition functions

• ▶️  Online playground

• ⚡️ avoids end-users bundling unused code

Definition functions (for example, in Vue with defineComponent) are increasingly common but do not play nice with tree-shaking. It's not possible to tell whether or not a function call which receives an object can be tree-shaken from a build, as it's possible there might be side effects.

Rollup supports /* @__PURE__ */ annotations to declare this from a library author's point of view, but it can be tricky when we know that every occurrence of a function call is pure.

This plugin will automatically inject the annotation before any occurrence of the function call, as well as injecting /* @__NO_SIDE_EFFECTS__ */ annotations in front of function declarations.

Install and add rollup-plugin-pure to your Vite or Rollup config.

pnpm add -D rollup-plugin-pure

import { PluginPure } from 'rollup-plugin-pure'
import { defineConfig } from 'vite'

export default defineConfig({
  plugins: [
    PluginPure({
      functions: ['defineComponent', /^define(Page|Meta)$/],
      include: [/(?<!im)pure\.js$/],
      // exclude: [],
      // sourcemap: true,
    }),
  ],
})

• Clone this repository
• Enable Corepack using corepack enable
• Install dependencies using pnpm install
• Stub module with pnpm dev:prepare
• Run pnpm dev to start playground in development mode

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Published under the MIT License.