devjar

react live preview in browser

Introduction

devjar is a library that enables you to live test and share your code snippets and examples with others. devjar will generate a live code editor where you can run your code snippets and view the results in real-time based on the provided code content of your React app.

Notice: devjar requires React 19 and only works for browser runtime at the moment. It will always render the default export component in index.js as the app entry.

Install

pnpm add devjar

React Code Runtime

<DevJar>

DevJar is a react component that allows you to develop and test your code directly in the browser, using a CDN to load your dependencies.

Props

• files: An object that specifies the files you want to include in your development environment.
• resolveModule: A function that maps module specifiers to browser-loadable module URLs.
• onError: Callback function of error event from the iframe sandbox. By default console.log.
• tailwindSrc: Optional Tailwind browser script URL. Pass false to disable Tailwind injection.

Example

import { DevJar } from 'devjar'

const CDN_HOST = 'https://esm.sh'

const files = {
  'index.js': `export default function App() { return 'hello world' }`
}

function App() {
  return (
    <DevJar
      files={files}
      resolveModule={(specifier) => {
        return `${CDN_HOST}/${specifier}`
      }}
    />
  )
}

useLiveCode(options)

A hook that provides lower-level control over the live code execution environment.

Parameters

• options
  • resolveModule(specifier): A function that receives a module specifier and returns the browser-loadable URL. For example, import React from 'react' will load React from skypack.dev/react.
  • tailwindSrc: Optional Tailwind browser script URL. Pass false to disable Tailwind injection.

Returns

• state
  • ref: A reference to the iframe element where the live coding will be executed.
  • error: An error message in case the live coding encounters an issue.
  • load(codeFiles): void: Loads code files and executes them as live code.

Example

import { useLiveCode } from 'devjar'

function Playground() {
  const { ref, error, load } = useLiveCode({
    // The CDN url of each imported module path in your code
    // e.g. `import React from 'react'` will load react from skypack.dev/react
    resolveModule(specifier) {
      return `https://cdn.skypack.dev/${specifier}`
    }
  })

  // logging failures
  if (error) {
    console.error(error)
  }

  // load code files and execute them as live code
  function run() {
    load({
      // `index.js` is the entry of every project
      'index.js': `export default function App() { return 'hello world' }`,

      // other relative modules can be used in the live coding
      './mod': `export default function Mod() { return 'mod' }`,
    })
  }

  // Attach the ref to an iframe element for runtime of code execution
  return (
    <div>
      <button onClick={run}>run</button>
      <iframe ref={ref} />
    </div>
  )
}

License

MIT