react-native/local-cli/server/middleware/getDevToolsMiddleware.js

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 */
'use strict';

const launchChrome = require('../util/launchChrome');

const {exec} = require('child_process');

function launchChromeDevTools(host, args = '') {
  var debuggerURL = 'http://' + host + '/debugger-ui' + args;
  console.log('Launching Dev Tools...');
  launchChrome(debuggerURL);
}

function escapePath(pathname) {
  // " Can escape paths with spaces in OS X, Windows, and *nix
  return '"' + pathname + '"';
}

function launchDevTools({host, projectRoots}, isChromeConnected) {
  // Explicit config always wins
  var customDebugger = process.env.REACT_DEBUGGER;
  if (customDebugger) {
    var projects = projectRoots.map(escapePath).join(' ');
    var command = customDebugger + ' ' + projects;
    console.log('Starting custom debugger by executing: ' + command);
    exec(command, function(error, stdout, stderr) {
      if (error !== null) {
        console.log('Error while starting custom debugger: ' + error);
      }
    });
  } else if (!isChromeConnected()) {
    // Dev tools are not yet open; we need to open a session
    launchChromeDevTools(host);
  }
}

module.exports = function(options, isChromeConnected) {
  return function(req, res, next) {
    var host = req.headers.host;
    if (req.url === '/launch-safari-devtools') {
      // TODO: remove `console.log` and dev tools binary
      console.log(
        'We removed support for Safari dev-tools. ' +
          'If you still need this, please let us know.',
      );
    } else if (req.url === '/launch-chrome-devtools') {
      // TODO: Remove this case in the future
      console.log(
        'The method /launch-chrome-devtools is deprecated. You are ' +
          ' probably using an application created with an older CLI with the ' +
          ' packager of a newer CLI. Please upgrade your application: ' +
          'https://facebook.github.io/react-native/docs/upgrading.html',
      );
      launchDevTools(options, isChromeConnected);
      res.end('OK');
    } else if (req.url === '/launch-js-devtools') {
      launchDevTools({...options, host}, isChromeConnected);
      res.end('OK');
    } else {
      next();
    }
  };
};