React Native Web Player Save

An interactive JavaScript sandbox

Project README

JavaScript Playgrounds

An interactive JavaScript sandbox. Try it!

Animated demo


This project provides a quick, visual way to experiment with JavaScript code. It's designed to be loaded as an iframe for easy inclusion in any webpage.

There are a variety of configuration options, including a React preset and a React Native preset.

I use this sandbox in my free educational guides:


The sandbox may be included on your site in one of two ways:

For legacy React Native-specific docs, see the v1 branch

As a React Component

If you're using React:

npm install --save javascript-playgrounds

# or

yarn add javascript-playgrounds


import Playground from 'javascript-playgrounds'

export default function App() {
  return <Playground style={{ width: 800, height: 500 }} />

This component is a wrapper around the iframe that handles encoding parameters for you. While it passes most props along to the iframe, it has a few extra props:

Title Description Default
style The style of the div which wraps the iframe (the iframe has 100% width and height). undefined
className The className of the div which wraps the iframe undefined
baseURL Optionally, specify a custom url to load the player from. This url should not include a hash. (see unpkg)

As an iframe

If you're not using React, include the sandbox in an iframe.


Configuration parameters should be passed as part of the hash string, after #data=. They should be JSON-encoded and then URI-encoded:

const parameters = { code: `console.log('Hello, world!')` }
const hashString = '#data=' + encodeURIComponent(JSON.stringify(parameters))

When used as an iframe, the easiest way to set the code parameter is to edit the code in the sandbox and copy and paste the url when you're done (the url updates automatically as you type).

For convenience, you may optionally pass the preset parameter in the url string directly, e.g. #preset=react&data=....


The sandbox accepts the following props/parameters.

Title Description Default
preset This sets reasonable defaults for other parameters. Options are javascript, react, and react-native. Experimental options are html and python (make sure to lock down your javascript-playgrounds library version when using experimental presets). 'javascript'
title An optional title for the editor pane. ''
code The code to show/run in the player. The sample app
files A map of { [filename]: code }. This will take precedence over code if given. undefined
entry The filename of the file that runs first. This is only relevant when showing multiple files with the files parameter. Defaults to index.js, or index.tsx if TypeScript is enabled. 'index.js' or 'index.tsx'
initialTab The filename of the tab to show by default. This is only relevant when showing multiple files with the files parameter. Defaults to the value of entry. entry
modules An array of external modules to make available to the sandbox. Each object in the array should be an object containing a name and url. As a shorthand, pass a string name to load a module from unpkg (${name}). More detail below. []
css An optional CSS string to apply within the workspace iframe. ''
styles An map of inline style objects, applied to various elements to customize the style of the UI. Example: { header: { backgroundColor: 'red' } } {}
strings A map of strings that appear in the UI. Example: { loading: 'Loading dependencies...' } {}
sharedEnvironment This affects how the iframes share data with one another, mainly for the "playgrounds" feature. When true, iframes will pass JavaScript objects back and forth, while when false, they'll pass serialized JSON. false
detectDependencies Should the player scan code files for imports and try to fetch them from unpkg? Only modules imported in the initial code are fetched (not those added while typing in the sandbox). true
fullscreen Show a button to enable fullscreen editing (in most configurations of panes). Note that the iframe must have the allowfullscreen attribute for this to work. false
compiler Settings for Babel {}
compiler.maxLoopIterations Throw an error if a loop iterates more than a certain amount of times. Set to 0 to disable. 1000
playground Settings for playgrounds (inline widgets that display runtime values) {}
playground.enabled Turn on playgrounds? false
playground.renderReactElements Render React elements? If false, will print the React element object, e.g. { type, props, key }, rather than render it. true
playground.debounceDuration How frequently widgets update. A little delay helps keep the UI feeling smoother. 200 (milliseconds)
typescript TypeScript settings {}
typescript.enabled Turn on TypeScript hover tooltip info? Defaults to false false
typescript.libs An array of default libraries to include, e.g. 'dom' and 'es2015'. We don't include some newer/esoteric ones by default, to reduce download size. See source code
typescript.types An array of additional type files to download. Each should be an object { name, url }. []
workspaces Add a tutorial-like sequence of sets of files, highlighting changes between each set. Each object in this array can contain: { title, description, workspace: { title, files, entry, initialTab } }. Properties in the workspace object will override those given as top level parameters. []
panes An array of UI panes to display. To display a pane without options, use a string. Otherwise, use an object with a type property. The available panes are: 'stack', 'editor', 'transpiler', 'player', 'workspaces', 'console'. Note that there must be a player pane for any code to run. For pane options, see below. ['editor', 'player']
responsivePaneSets An array of { maxWidth, panes } objects to show at different responsive breakpoints. The iframe will use the first set where the maxWidth is greater than the current window width. The top-level panes parameter has maxWidth: Infinity so that it's used by default if there's no matching set of panes. []
targetOrigin If passed, the sandbox will call parent.postMessage(JSON.stringify(data), targetOrigin) on code changes. undefined
Examples of loading modules:
  • To load a CommonJS require-style module, the name is the require(name) name, and the second is the source url. E.g. to load moment.js: set modules to the value [{ name: 'moment', url: '' }]
  • To load a component as a property on window, also pass a globalName, which will be the window property name (e.g. window.moment). E.g. to load moment.js this way: set modules to the value [{ name: 'moment', globalName: 'moment', url: '' }]

Pane options

All panes support the following options:

Title Description Default
style The inline styles for this specific pane, merged with those passed in the top-level styles object if given. undefined
title An optional title for this pane. If used on an 'editor' pane, this will override a top-level title, if one was given. ''

Each pane additionally supports pane-specific options. For more detail:

The player pane

Display the running app, optionally with the image of a phone around it.

Title Description Default
platform One of ios, android, or web. When web, no phone image is displayed. 'ios'
width The width of the device. This has no effect if the platform is web. 210px
scale Zoom the device screen. This has no effect if the platform is web. 1
assetRoot Specifies the root url for asset requires. E.g. to require http://localhost:8080/images/hello.png, you could set assetRoot to 'http://localhost:8080/' and write require('./images/hello.png') in your code. ''
css An optional CSS string to apply within the player's iframe. ''
styleSheet One of reset or none. When reset, the meyerweb CSS reset is applied to the player's iframe. 'reset'
statusBarHeight Display a rectangle at the top of the phone screen, mimicking a status bar. 0px
statusBarColor The color of the fake status bar. 'black'
prelude JavaScript code that runs before the entry file. ''
modules Pane-specific modules, in addition to those passed at the top level. []
console Display an embedded console in this pane. See the console options below. Additionally, the embedded version of the console has the following properties... {}
console.visible Show the console? false
console.maximized Show the console over the entire player? false
console.collapsible Allow collapsing the console via a toggle button. true

The console pane

Show the output console.log, similar to the Chrome inspector. This can be a separate pane, or embedded in the player pane.

Title Description Default
showFileName Show the file name containing the console.log. false
showLineNumber Show the line number of the console.log. true
renderReactElements Render React elements, instead of displaying element JSON. false

The stack pane

A nested stack of panes.

Title Description Default
children An array of panes, just like the top level panes parameter. []

The editor pane

None at the moment.

The transpiler pane

None at the moment.

The workspaces pane

None at the moment.


This project contains static assets that run standalone in the browser. You don't need a server, unless you want to host the assets yourself.


The recommended host is, which is a CDN that serves content from the npm registry. The examples in this README all point to:


Note that unpkg resolves semver versions in the url


These examples were created by loading the demo page and running roughly the following JS in the console:

location.href.slice(0, location.href.indexOf('#')) +
  '#data=' +
      title: 'Custom title',
      panes: [
        { type: 'player', platform: 'android', modules: ['moment'] },



yarn dev
# => localhost:8080


yarn build


Contributions are welcome, but if you're planning to add features, I recommend opening an issue describing the change first.

I maintain this project specifically for my educational guides, so if it's a feature I wouldn't use, I might not want to maintain it. It also may take me a little while to get to reviewing.


3-Clause BSD

Open Source Agenda is not affiliated with "React Native Web Player" Project. README Source: dabbott/javascript-playgrounds
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