svelte/documentation/docs/06-legacy/01-svelte-register.md

title
svelte/register

This API is removed in Svelte 4. require hooks are deprecated and current Node versions understand ESM. Use a bundler like Vite or our full-stack framework SvelteKit instead to create JavaScript modules from Svelte components.

To render Svelte components in Node.js without bundling, use require('svelte/register'). After that, you can use require to include any .svelte file.

// @noErrors
require('svelte/register');

const App = require('./App.svelte').default;

// ...

const { html, css, head } = App.render({ answer: 42 });

The .default is necessary because we're converting from native JavaScript modules to the CommonJS modules recognised by Node. Note that if your component imports JavaScript modules, they will fail to load in Node and you will need to use a bundler instead.

To set compile options, or to use a custom file extension, call the register hook as a function:

// @noErrors
require('svelte/register')({
	extensions: ['.customextension'], // defaults to ['.html', '.svelte']
	preserveComments: true
});