vite-plugin-iife

Vite plugin for simple IIFE-compiled script imports.

Overview

Sometimes you need a small snippet of code to run in a specific place at at a specific time during a page's loading process to achieve a specific effect or prevent the dreaded FOUC.

Running scripts as modules is great, but by design they are unavoidably executed with an implicit defer, and build systems can make it tricky to get a single chunk of code to behave differently.

This plugin lets you write scripts to be inlined using either JavaScript or TypeScript, and get a minified JavaScript IIFE snippet of code via an import statement, which makes it easy to integrate with static site generators:

import inlineIifeSnippet from './some-script.ts?iife'

// Logs the raw IIFE-compiled code from some-script.ts:
console.log(inlineIifeSnippet)

Installation

1. Install the plugin package

Assuming you're starting with a Vite project of some flavor:

npm install --save-dev vite-plugin-iife

2. Add the plugin to your vite.config file

// Vite.config.ts
import { defineConfig } from 'vite'
import iife from 'vite-plugin-iife'

export default defineConfig({
  plugins: [iife()],
})

3. Configure TypeScript

Skip this step if you're using plain JavaScript.

Add the extension declarations to your types in tsconfig.json:

{
  "compilerOptions": {
    "types": ["vite-plugin-iife/ext"]
  }
}

Alternately, you can add a triple-slash package dependency directive to your global types file (e.g. env.d.ts or similar):

/// <reference types="vite-plugin-iife/ext" />

This step should take care of errors like:

Cannot find module './test-script.ts?iife' or its corresponding type declarations.ts(2307)

Usage

IIFE string imports

Append ?iife to any script import string to receive the IIFE-compiled code as a default export string:

// Import contents of some-script.ts as an IIFE-compiled JavaScript string
import iifeSnippet from './some-script.ts?iife'

// Inject the IIFE code in a `<script>` tag
const script = document.createElement('script')
script.textContent = iifeSnippet
document.head.append(script)

IIFE file URL imports

Append ?iife&url to get a URL to the IIFE-compiled file instead of the code string. This is useful when you want to load the script via <script src=""> rather than inlining it:

// Import contents of some-script.ts to an IIFE-compiled JavaScript file and return its URL
import iifeUrl from './some-script.ts?iife&url'

// Create a script tag and set the source to the IIFE file URL
const script = document.createElement('script')
script.src = iifeUrl
document.head.append(script)

This follows Vite's convention for ?url imports on other asset types.

Summary

| Import | Returns | Use case | | ----------- | ------------------- | --------------------------------------- | | ?iife | IIFE code as string | Inline <script> tags, SSR templates | | ?iife&url | URL to IIFE file | <script src=""> tags, dynamic loading |

Since there's no code splitting or externalization of dependencies, vite-plugin-iife is only recommended for small and relatively self-contained scripts. The verbose option can help you keep tabs on the output size during development.

Plugin options

The plugin accepts a few options in its initialization function in your vite.config file. The options object type is exported as IifePluginOptions.

| Key | Type | Description | Default | | --------- | ------------------------- | ------------------------------------------------------------------- | ------- | | minify | true \| false \| 'auto' | Minify output. The 'auto' value only minifies on production builds. | 'auto' | | verbose | boolean | Log information to the console. | false |

Maintainers

@kitschpatrol

Contributing

Issues and pull requests are welcome.

License

MIT © Eric Mika