README
sandpack-client
A bundler that completely works in the browser and takes advantage of it.
Why?
Online code playgrounds are getting more popular: they provide an easy way to play with code without installation.
As CodeSandbox came along, it had a pretty basic bundler. However, as CodeSandbox got more popular its bundler got more advanced. Nowadays the bundler is used for all kinds of bigger web projects, and it would be a shame if others couldn't use the functionality.
This library acts as an interface with the bundler of CodeSandbox. It allows you to run any code on a web page, from Vue projects to React projects to Parcel projects. With everything that CodeSandbox supports client side as well.
So what can this bundler do?
This is a list of features that the bundler supports out of the box, the list may be outdated.
- Hot Module Reloading API (
module.hot
) - npm dependencies
- Most common transpilers (vue, babel, typescript, css, scss, less, stylus, parcel, etc...)
- Parallel transpiling
- On-demand transpiler loading
- Webpack loader syntax (
!raw-loader!./test.js
) - Friendly error overlay (using
create-react-app
overlay) - Transpilation result caching
- HTML/CSS entry points
Example usage
This repo serves as an interface to communicate with the bundler. The bundler
itself is hosted on {version}-sandpack.codesandbox.io
and is heavily cached by
a CDN. We also included the necessary files under sandpack
if you want to host
the bundler yourself.
Using the Client
The Client is a class implementation, you can import it from the package.
import { Client } from 'smooshpack';
// There are two ways of initializing a preview, you can give it either an
// iframe element or a selector of an element to create an iframe on.
const client = new Client(
'#preview', // iframe selector or element itself
{
files: {
'/index.js': {
code: `console.log(require('uuid'))`,
},
},
entry: '/index.js',
dependencies: {
uuid: 'latest',
},
} /* We support a third parameter for advanced options, you can find more info below */
);
// When you make a change you can just run `updatePreview`, we'll automatically discover
// which files have changed and hot reload them.
client.updatePreview({
files: {
'/index.js': {
code: `console.log('New Text!')`,
},
},
entry: '/index.js',
dependencies: {
uuid: 'latest',
},
});
If you specify a package.json
in the list of files we will use that as source
of truth. Otherwise, we infer dependencies
and entry
from it:
// We infer dependencies and the entry point from package.json
const PACKAGE_JSON_CODE = JSON.stringify(
{
title: 'test',
main: 'index.js',
dependencies: {
uuid: 'latest',
},
},
null,
2
);
// Give it either a selector or an iframe element as first argument, the second arguments are the files
const client = new Client('#preview', {
files: {
'/index.js': {
code: `console.log(require('uuid'))`,
},
'/package.json': {
code: PACKAGE_JSON_CODE,
},
},
});
SandboxInfo
The second argument in the constructor of Client
is all sandbox info. It has
this structure:
{
/**
* Files, keys are paths.
**/
files: {
[path: string]: {
code: string
}
},
/**
* Dependencies, supports npm and GitHub dependencies
**/
dependencies?: {
[dependencyName: string]: string
},
/**
* Default file to evaluate
**/
entry?: string,
/**
* The sandbox template to use, this is inferred from the files and package.json if not specified
**/
template?: string
}
ClientOptions
The third argument in the constructor of Client
is extra options. Here you can
pass custom bundling/evaluation options or instructions for what and how to
render inside the iframe:
{
/**
* Location of the bundler. Defaults to `${version}-sandpack.codesandbox.io`
*/
bundlerURL?: string;
/**
* Width/Height of the iframe.
*/
width?: string;
height?: string;
/**
* If we should skip the third step: evaluation. Useful if you only want to see
* transpiled results
*/
skipEval?: boolean;
/**
* Boolean flags to trigger certain UI elements in the bundler
*/
showOpenInCodeSandbox?: boolean;
showErrorScreen?: boolean;
showLoadingScreen?: boolean;
}
Client API
The client instance has several helper functions you can call.
updatePreview
Send new content like files and dependencies, to the preview. It will
automatically hot update the preview with the new files and options. Accepts a
single argument sandboxInfo
of type SandboxInfo
.
updateOptions
Updates the given options and then updates the preview. Accepts a single
argument options
of type ClientOptions
.
dispatch
Dispatch an event to the bundler and all other listeners. Accepts a single
argument, which is the data to send. The dispatch
function will pass the
internal id
of the client, so only the bundler that performed the handshake
with this client instance will respond.
client.dispatch({ type: 'refresh' }); // sends a refresh action to the bundler
listen
Listens to events coming from the bundler that performed the handshake with this
client instance. Uses the internal id
to filter events coming from other
bundlers.
client.listen(message => {
if (message.type === 'status') {
console.log(message.status);
}
});
getCodeSandboxURL
Create a sandbox from the current files and return an object in this form:
{
sandboxId: sandbox_id,
editorUrl: `https://codesandbox.io/s/${sandbox_id}`,
embedUrl: `https://codesandbox.io/embed/${sandbox_id}`,
}
import
?
Why is the bundler hosted externally and not a simple We have three reasons to host the bundler of sandpack externally:
Security
The bundler evaluates and transpiles all files in an iframe under a different subdomain. This is important, because it prevents attackers from tampering with cookies of the host domain when evaluating code.
Performance
We heavily make use of Web Workers for transpilations. Almost all our transpilation happens in web workers, and there is no easy way yet to bundle this in a library.
Bundle Size
Another reason to host the bundler externally is because of code splitting: we
split all our transpilers away and load them on-demand. If a user doesn't use
sass
we won't load the transpiler. This wouldn't be possible if we would give
one big JS file as the library.
Offline Support
We use Service Workers to download all transpilers in the background, so the next time a user visits your website they don't have to download the bundler anymore and it can be used offline. This is possible because we host the service worker externally.
I want to highlight that you can also host the bundler by yourself, all necessary files are in the
sandpack
folder.
For React developers
If you want to integrate the sandpack bundler into your React project, we recomment you check out the sandpack-react package, which has all the components and hooks you need for building an instant code running experience for your users.