StackBlitz SDK Patterns

Overview

Production patterns for the WebContainer API: singleton boot, file system CRUD, process spawning and management, jsh interactive shell, and the StackBlitz SDK for embedding projects.

Instructions

Step 1: Singleton WebContainer Instance

import { WebContainer } from '@webcontainer/api';

let instance: WebContainer | null = null;

export async function getWebContainer(): Promise<WebContainer> {
  if (!instance) {
    instance = await WebContainer.boot();
  }
  return instance;
}

// Teardown
export async function teardownWebContainer() {
  if (instance) {
    instance.teardown();
    instance = null;
  }
}

Step 2: File System Operations

const wc = await getWebContainer();

// Write file
await wc.fs.writeFile('/src/app.ts', 'export const hello = "world";');

// Read file
const content = await wc.fs.readFile('/src/app.ts', 'utf-8');

// Read directory
const entries = await wc.fs.readdir('/src', { withFileTypes: true });
entries.forEach(entry => {
  console.log(`${entry.name} (${entry.isDirectory() ? 'dir' : 'file'})`);
});

// Create directory
await wc.fs.mkdir('/src/components', { recursive: true });

// Delete file
await wc.fs.rm('/src/old.ts');

// Delete directory
await wc.fs.rm('/dist', { recursive: true });

// Watch for changes
wc.fs.watch('/src', { recursive: true }, (event, filename) => {
  console.log(`${event}: ${filename}`);
});

Step 3: Process Management

// Spawn a process
const proc = await wc.spawn('node', ['script.js']);

// Stream stdout
const reader = proc.output.getReader();
while (true) {
  const { done, value } = await reader.read();
  if (done) break;
  console.log(value);
}

// Write to stdin
const writer = proc.input.getWriter();
await writer.write('user input\n');
await writer.close();

// Wait for exit
const exitCode = await proc.exit;

// Kill a process
proc.kill();

Step 4: jsh Interactive Shell

// jsh is WebContainer's built-in shell
const jshProcess = await wc.spawn('jsh', {
  terminal: { cols: 80, rows: 24 },
});

// Connect to xterm.js
import { Terminal } from 'xterm';
const terminal = new Terminal();
terminal.open(document.getElementById('terminal')!);

jshProcess.output.pipeTo(new WritableStream({
  write(data) { terminal.write(data); },
}));

terminal.onData((data) => {
  const writer = jshProcess.input.getWriter();
  writer.write(data);
  writer.releaseLock();
});

Step 5: StackBlitz SDK (Embedding)

import sdk from '@stackblitz/sdk';

// Embed an existing project
sdk.embedProjectId('container', 'vitejs-vite-template', {
  height: 500,
  openFile: 'src/App.tsx',
  terminalHeight: 30,
});

// Embed from GitHub
sdk.embedGithubProject('container', 'user/repo', {
  openFile: 'README.md',
});

// Create new project programmatically
sdk.embedProject('container', {
  title: 'My Project',
  template: 'node',
  files: {
    'index.js': 'console.log("Hello!")',
    'package.json': '{"name":"demo","scripts":{"start":"node index.js"}}',
  },
});

Error Handling

Pattern	Use Case	Benefit
Singleton boot	Multiple components need WC	Only one instance allowed per page
Process kill on teardown	Page navigation	Prevents orphaned processes
fs.watch	Live preview	Auto-rebuild on file changes
jsh + xterm.js	Terminal emulator	Full shell experience in browser

Resources

Next Steps

Apply patterns in stackblitz-core-workflow-a.