service-worker.js

// transpile JSX using babel so it can be run in the browser, you don't need to edit this
// if you do edit this file, call `await window.serviceWorkerRegistration.unregister()` in the browser to update it

let curVersion = 0

self.addEventListener('install', e => {
  self.skipWaiting()
  e.waitUntil(getBabel())
})
self.addEventListener('fetch', e => e.respondWith(handleRequest(e.request)))

async function getBabel() {
  const r = await fetch('https://unpkg.com/@babel/standalone/babel.min.js')
  eval(await r.text())
}

async function handleRequest(request) {
  if (typeof Babel === 'undefined') {
    await getBabel()
  }
  const url = new URL(request.url)
  const r = await fetch(request)
  if (r.status === 200 && url.host === location.host && (url.pathname.endsWith('.jsx') || url.pathname.endsWith('.js')) && !url.pathname.startsWith('./lib') && !url.pathname.startsWith('/lib') && !url.pathname.includes('/lib')) {
    const parsedVersion = request.url.split('?cryptic-version=')[1] || undefined
    if (!!parsedVersion && parsedVersion !== curVersion) {
      curVersion = parsedVersion
    }
    let jsx = await r.text()
    jsx = jsx.replaceAll(/(?<=import.*)(.js')/g, `.js?cryptic-version=${curVersion}'`)
    const js = Babel.transform(jsx, {presets: ['react']}).code
    return new Response(js, r)
  } else {
    return r
  }
}