Chrome Extension template

Template for Chrome Extension MV3+ using Vite + Svelte + TypeScript. It is set to have a background worker script and a popup action.

Types

The chrome types are provided with "chrome-types" package.

Scripts

• dev - run dev server, will open popup entry point in a browser. The chrome namespace will not be available.
• build - builds the extension output. Use this to deploy extension, you can also use this folder to load unpacked into your browser in dev mode.
• check - performs svelte-check diagnostics on the code.

Manifest

Manifest and extension static assets (like icons) are in the public folder. Manifest is in it's 3 version.

Background script

If you dont need an background worker script then remove src/background.ts and remove this entry from vite.config.ts's input list: input: 'popup.html',

Recommended IDE Setup

VS Code + Svelte.

Need an official Svelte framework?

Check out SvelteKit, which is also powered by Vite. Deploy anywhere with its serverless-first approach and adapt to various platforms, with out of the box support for TypeScript, SCSS, and Less, and easily-added support for mdsvex, GraphQL, PostCSS, Tailwind CSS, and more.

Technical considerations

Why use this over SvelteKit?

• It brings its own routing solution which might not be preferable for some users.
• It is first and foremost a framework that just happens to use Vite under the hood, not a Vite app.

This template contains as little as possible to get started with Vite + TypeScript + Svelte, while taking into account the developer experience with regards to HMR and intellisense. It demonstrates capabilities on par with the other create-vite templates and is a good starting point for beginners dipping their toes into a Vite + Svelte project.

Should you later need the extended capabilities and extensibility provided by SvelteKit, the template has been structured similarly to SvelteKit so that it is easy to migrate.

Why global.d.ts instead of compilerOptions.types inside jsconfig.json or tsconfig.json?

Setting compilerOptions.types shuts out all other types not explicitly listed in the configuration. Using triple-slash references keeps the default TypeScript setting of accepting type information from the entire workspace, while also adding svelte and vite/client type information.

Why include .vscode/extensions.json?

Other templates indirectly recommend extensions via the README, but this file allows VS Code to prompt the user to install the recommended extension upon opening the project.

Why enable allowJs in the TS template?

While allowJs: false would indeed prevent the use of .js files in the project, it does not prevent the use of JavaScript syntax in .svelte files. In addition, it would force checkJs: false, bringing the worst of both worlds: not being able to guarantee the entire codebase is TypeScript, and also having worse typechecking for the existing JavaScript. In addition, there are valid use cases in which a mixed codebase may be relevant.

Why is HMR not preserving my local component state?

HMR state preservation comes with a number of gotchas! It has been disabled by default in both svelte-hmr and @sveltejs/vite-plugin-svelte due to its often surprising behavior. You can read the details here.

If you have state that's important to retain within a component, consider creating an external store which would not be replaced by HMR.

// store.ts
// An extremely simple external store
import { writable } from 'svelte/store';
export default writable(0);