npm install @codesandbox/node-emulator

import { NodeEmulator } from '@codesandbox/node-emulator';

async function usage() {
  const emulator = new NodeEmulator('https://...', {
    iframe: document.getElementById('my-frame'),
  });

  await emulator.connect();
}

See the full list of API for more methods.

Connects to a deployed Node emulator instance. Returns a Promise once the connection is established and the emulator iframe has established a message channel with the consumer.

await emulator.connect();

Populates the File system with the initial state of files. Returns a Promise once the files are populated and the worker is finished.

await emulator.fs.init({
  // Each key in this object is a relative path to the file,
  // and each value if an ArrayBuffer of the file's contents.
  '/src/index.js': new Uint8Array([1, 2, 3])
}

It reads asynchronously a content file.

await emulator.fs.readFile("/index.js").then(value => value.toString())

await emulator.fs.readFile("/index.js", "utf8")

It writes asynchronously a content to a file, which will replace the file if it already exists.

await emulator.fs.writeFile("/index.js", new Uint8Array([1, 2, 3]))

await emulator.fs.writeFile("/index.js", "Hello World", "utf8")

It asynchronously watches for changes on a file or a directory given a Glob matcher. Each change event it returns the filename and an event type that could be: rename, delete, create or change.

await emulator.fs.watch("/**/*", (evt) => {
  switch (evt.type) {
    case 'create':
    case 'remove':
    case 'change':
      console.log(evt.type, evt.path);
      break;
    case 'rename':
      console.log(evt.type, evt.oldPath, evt.newPath);
      break;
    case 'close':
      console.log('Watcher closed');
      break;
  }
})

It creates a new ShellProcess, which can perform some actions in this shell.

const shellProcess = channel.shell.create();

Executes a given command. Returns a Promise that resolves to an object with the shell information representing a shell process running in the worker.

const { id: shellId } = await shellProcess.runCommand('node', ['index.js']);

It returns running when a worker is running (but not necessarily a preview opened) and idle when the process has been exited or restarted (but running after successfully initializing again).

It terminates the Worker and closes the preview port.

await shellProcess.runCommand('node', ['src/index.js']);

await shellProcess.exit()

It returns an URL preview for a given port. The second argument is a timeout value, which will trigger rejecting the promise if the port fails (it defaults to 10s).

const { url, sourceShellId } = await emulator.preview.waitForPort(3000)

It returns an URL preview for a given shell id. The second argument is a timeout value, which will trigger rejecting the promise if the port fails (it defaults to 10s).

const { id } = await emulator.shell.runCommand('node', ['src/index.js']);
const { url, port } = await emulator.preview.getByShellId(id)

At the moment, Node emulator only supports evaluating JavaScript modules.