safe-react/scripts/start.js

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process.env.NODE_ENV = 'development';
// Load environment variables from .env file. Suppress warnings using silent
// if this file is missing. dotenv will never modify any environment variables
// that have already been set.
// https://github.com/motdotla/dotenv
require('dotenv').config({silent: true});
var chalk = require('chalk');
var webpack = require('webpack');
var WebpackDevServer = require('webpack-dev-server');
var historyApiFallback = require('connect-history-api-fallback');
var httpProxyMiddleware = require('http-proxy-middleware');
var detect = require('detect-port');
var clearConsole = require('react-dev-utils/clearConsole');
var checkRequiredFiles = require('react-dev-utils/checkRequiredFiles');
var formatWebpackMessages = require('react-dev-utils/formatWebpackMessages');
var getProcessForPort = require('react-dev-utils/getProcessForPort');
var openBrowser = require('react-dev-utils/openBrowser');
var pathExists = require('path-exists');
var config = require('../config/webpack.config.dev');
var paths = require('../config/paths');
var useYarn = pathExists.sync(paths.yarnLockFile);
var cli = useYarn ? 'yarn' : 'npm';
var isInteractive = process.stdout.isTTY;
// Warn and crash if required files are missing
if (!checkRequiredFiles([paths.appHtml, paths.appIndexJs])) {
process.exit(1);
}
// Tools like Cloud9 rely on this.
var DEFAULT_PORT = process.env.PORT || 3000;
var compiler;
var handleCompile;
// You can safely remove this after ejecting.
// We only use this block for testing of Create React App itself:
var isSmokeTest = process.argv.some(arg => arg.indexOf('--smoke-test') > -1);
if (isSmokeTest) {
handleCompile = function (err, stats) {
if (err || stats.hasErrors() || stats.hasWarnings()) {
process.exit(1);
} else {
process.exit(0);
}
};
}
function setupCompiler(host, port, protocol) {
// "Compiler" is a low-level interface to Webpack.
// It lets us listen to some events and provide our own custom messages.
compiler = webpack(config, handleCompile);
// "invalid" event fires when you have changed a file, and Webpack is
// recompiling a bundle. WebpackDevServer takes care to pause serving the
// bundle, so if you refresh, it'll wait instead of serving the old one.
// "invalid" is short for "bundle invalidated", it doesn't imply any errors.
compiler.plugin('invalid', function() {
if (isInteractive) {
clearConsole();
}
console.log('Compiling...');
});
var isFirstCompile = true;
// "done" event fires when Webpack has finished recompiling the bundle.
// Whether or not you have warnings or errors, you will get this event.
compiler.plugin('done', function(stats) {
if (isInteractive) {
clearConsole();
}
// We have switched off the default Webpack output in WebpackDevServer
// options so we are going to "massage" the warnings and errors and present
// them in a readable focused way.
var messages = formatWebpackMessages(stats.toJson({}, true));
var isSuccessful = !messages.errors.length && !messages.warnings.length;
var showInstructions = isSuccessful && (isInteractive || isFirstCompile);
if (isSuccessful) {
console.log(chalk.green('Compiled successfully!'));
}
if (showInstructions) {
console.log();
console.log('The app is running at:');
console.log();
console.log(' ' + chalk.cyan(protocol + '://' + host + ':' + port + '/'));
console.log();
console.log('Note that the development build is not optimized.');
console.log('To create a production build, use ' + chalk.cyan(cli + ' run build') + '.');
console.log();
isFirstCompile = false;
}
// If errors exist, only show errors.
if (messages.errors.length) {
console.log(chalk.red('Failed to compile.'));
console.log();
messages.errors.forEach(message => {
console.log(message);
console.log();
});
return;
}
// Show warnings if no errors were found.
if (messages.warnings.length) {
console.log(chalk.yellow('Compiled with warnings.'));
console.log();
messages.warnings.forEach(message => {
console.log(message);
console.log();
});
// Teach some ESLint tricks.
console.log('You may use special comments to disable some warnings.');
console.log('Use ' + chalk.yellow('// eslint-disable-next-line') + ' to ignore the next line.');
console.log('Use ' + chalk.yellow('/* eslint-disable */') + ' to ignore all warnings in a file.');
}
});
}
// We need to provide a custom onError function for httpProxyMiddleware.
// It allows us to log custom error messages on the console.
function onProxyError(proxy) {
return function(err, req, res){
var host = req.headers && req.headers.host;
console.log(
chalk.red('Proxy error:') + ' Could not proxy request ' + chalk.cyan(req.url) +
' from ' + chalk.cyan(host) + ' to ' + chalk.cyan(proxy) + '.'
);
console.log(
'See https://nodejs.org/api/errors.html#errors_common_system_errors for more information (' +
chalk.cyan(err.code) + ').'
);
console.log();
// And immediately send the proper error response to the client.
// Otherwise, the request will eventually timeout with ERR_EMPTY_RESPONSE on the client side.
if (res.writeHead && !res.headersSent) {
res.writeHead(500);
}
res.end('Proxy error: Could not proxy request ' + req.url + ' from ' +
host + ' to ' + proxy + ' (' + err.code + ').'
);
}
}
function addMiddleware(devServer) {
// `proxy` lets you to specify a fallback server during development.
// Every unrecognized request will be forwarded to it.
var proxy = require(paths.appPackageJson).proxy;
devServer.use(historyApiFallback({
// Paths with dots should still use the history fallback.
// See https://github.com/facebookincubator/create-react-app/issues/387.
disableDotRule: true,
// For single page apps, we generally want to fallback to /index.html.
// However we also want to respect `proxy` for API calls.
// So if `proxy` is specified, we need to decide which fallback to use.
// We use a heuristic: if request `accept`s text/html, we pick /index.html.
// Modern browsers include text/html into `accept` header when navigating.
// However API calls like `fetch()` wont generally accept text/html.
// If this heuristic doesnt work well for you, dont use `proxy`.
htmlAcceptHeaders: proxy ?
['text/html'] :
['text/html', '*/*']
}));
if (proxy) {
if (typeof proxy !== 'string') {
console.log(chalk.red('When specified, "proxy" in package.json must be a string.'));
console.log(chalk.red('Instead, the type of "proxy" was "' + typeof proxy + '".'));
console.log(chalk.red('Either remove "proxy" from package.json, or make it a string.'));
process.exit(1);
}
// Otherwise, if proxy is specified, we will let it handle any request.
// There are a few exceptions which we won't send to the proxy:
// - /index.html (served as HTML5 history API fallback)
// - /*.hot-update.json (WebpackDevServer uses this too for hot reloading)
// - /sockjs-node/* (WebpackDevServer uses this for hot reloading)
// Tip: use https://jex.im/regulex/ to visualize the regex
var mayProxy = /^(?!\/(index\.html$|.*\.hot-update\.json$|sockjs-node\/)).*$/;
// Pass the scope regex both to Express and to the middleware for proxying
// of both HTTP and WebSockets to work without false positives.
var hpm = httpProxyMiddleware(pathname => mayProxy.test(pathname), {
target: proxy,
logLevel: 'silent',
onProxyReq: function(proxyReq, req, res) {
// Browers may send Origin headers even with same-origin
// requests. To prevent CORS issues, we have to change
// the Origin to match the target URL.
if (proxyReq.getHeader('origin')) {
proxyReq.setHeader('origin', proxy);
}
},
onError: onProxyError(proxy),
secure: false,
changeOrigin: true,
ws: true
});
devServer.use(mayProxy, hpm);
// Listen for the websocket 'upgrade' event and upgrade the connection.
// If this is not done, httpProxyMiddleware will not try to upgrade until
// an initial plain HTTP request is made.
devServer.listeningApp.on('upgrade', hpm.upgrade);
}
// Finally, by now we have certainly resolved the URL.
// It may be /index.html, so let the dev server try serving it again.
devServer.use(devServer.middleware);
}
function runDevServer(host, port, protocol) {
var devServer = new WebpackDevServer(compiler, {
// Enable gzip compression of generated files.
compress: true,
// Silence WebpackDevServer's own logs since they're generally not useful.
// It will still show compile warnings and errors with this setting.
clientLogLevel: 'none',
// By default WebpackDevServer serves physical files from current directory
// in addition to all the virtual build products that it serves from memory.
// This is confusing because those files wont automatically be available in
// production build folder unless we copy them. However, copying the whole
// project directory is dangerous because we may expose sensitive files.
// Instead, we establish a convention that only files in `public` directory
// get served. Our build script will copy `public` into the `build` folder.
// In `index.html`, you can get URL of `public` folder with %PUBLIC_PATH%:
// <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
// In JavaScript code, you can access it with `process.env.PUBLIC_URL`.
// Note that we only recommend to use `public` folder as an escape hatch
// for files like `favicon.ico`, `manifest.json`, and libraries that are
// for some reason broken when imported through Webpack. If you just want to
// use an image, put it in `src` and `import` it from JavaScript instead.
contentBase: paths.appPublic,
// Enable hot reloading server. It will provide /sockjs-node/ endpoint
// for the WebpackDevServer client so it can learn when the files were
// updated. The WebpackDevServer client is included as an entry point
// in the Webpack development configuration. Note that only changes
// to CSS are currently hot reloaded. JS changes will refresh the browser.
hot: true,
// It is important to tell WebpackDevServer to use the same "root" path
// as we specified in the config. In development, we always serve from /.
publicPath: config.output.publicPath,
// WebpackDevServer is noisy by default so we emit custom message instead
// by listening to the compiler events with `compiler.plugin` calls above.
quiet: true,
// Reportedly, this avoids CPU overload on some systems.
// https://github.com/facebookincubator/create-react-app/issues/293
watchOptions: {
ignored: /node_modules/
},
// Enable HTTPS if the HTTPS environment variable is set to 'true'
https: protocol === "https",
host: host
});
// Our custom middleware proxies requests to /index.html or a remote API.
addMiddleware(devServer);
// Launch WebpackDevServer.
devServer.listen(port, (err, result) => {
if (err) {
return console.log(err);
}
if (isInteractive) {
clearConsole();
}
console.log(chalk.cyan('Starting the development server...'));
console.log();
if (isInteractive) {
openBrowser(protocol + '://' + host + ':' + port + '/');
}
});
}
function run(port) {
var protocol = process.env.HTTPS === 'true' ? "https" : "http";
var host = process.env.HOST || 'localhost';
setupCompiler(host, port, protocol);
runDevServer(host, port, protocol);
}
// We attempt to use the default port but if it is busy, we offer the user to
// run on a different port. `detect()` Promise resolves to the next free port.
detect(DEFAULT_PORT).then(port => {
if (port === DEFAULT_PORT) {
run(port);
return;
}
if (isInteractive) {
clearConsole();
var existingProcess = getProcessForPort(DEFAULT_PORT);
run(port);
} else {
console.log(chalk.red('Something is already running on port ' + DEFAULT_PORT + '.'));
}
});