1/**2 * Copyright (c) Meta Platforms, Inc. and affiliates.3 *4 * This source code is licensed under the MIT license found in the5 * LICENSE file in the root directory of this source tree.6 *7 */89import {Writable} from 'stream';10import * as React from 'react';11import {renderToPipeableStream} from 'react-dom/server';12import App from '../src/App';13import {ABORT_DELAY} from './delays';1415// In a real setup, you'd read it from webpack build stats.16let assets = {17  'main.js': '/main.js',18  'main.css': '/main.css',19};2021function HtmlWritable(options) {22  Writable.call(this, options);23  this.chunks = [];24  this.html = '';25}2627HtmlWritable.prototype = Object.create(Writable.prototype);28HtmlWritable.prototype.getHtml = function getHtml() {29  return this.html;30};31HtmlWritable.prototype._write = function _write(chunk, encoding, callback) {32  this.chunks.push(chunk);33  callback();34};35HtmlWritable.prototype._final = function _final(callback) {36  this.html = Buffer.concat(this.chunks).toString();37  callback();38};3940module.exports = function render(url, res) {41  let writable = new HtmlWritable();42  res.socket.on('error', error => {43    console.error('Fatal', error);44  });45  let didError = false;46  let didFinish = false;4748  writable.on('finish', () => {49    // If something errored before we started streaming, we set the error code appropriately.50    res.statusCode = didError ? 500 : 200;51    res.setHeader('Content-type', 'text/html');52    res.send(writable.getHtml());53  });5455  const {pipe, abort} = renderToPipeableStream(<App assets={assets} />, {56    bootstrapScripts: [assets['main.js']],57    onAllReady() {58      // Full completion.59      // You can use this for SSG or crawlers.60      didFinish = true;61    },62    onShellReady() {63      // If something errored before we started streaming, we set the error code appropriately.64      pipe(writable);65    },66    onShellError(x) {67      // Something errored before we could complete the shell so we emit an alternative shell.68      res.statusCode = 500;69      res.send('<!doctype><p>Error</p>');70    },71    onError(x) {72      didError = true;73      console.error(x);74    },75  });76  // Abandon and switch to client rendering if enough time passes.77  // Try lowering this to see the client recover.78  setTimeout(() => {79    if (!didFinish) {80      abort();81    }82  }, ABORT_DELAY);83};