React第一篇： 搭建React + nodejs + express框架

前提： 需要安装Node.js (>6)版本

---

1.cmd进到本地某个目录， 逐行输入以下指令（以下括号为注释）

npm install -g create-react-app   (全局安装create-react-app， 默认会安装在C盘个人用户下）

create-react-app my-app （此步安装my-app以及需要的模块到当前文件夹下）

cd my-app （进入到my-app目录）

npm start　（启动react项目Demo，可输入localhost:3000进入看demo）

---

2.开发模式选择用npm start

①首先为什么呢？这涉及到热模块更换（HMR），笼统的说就是更改了JS代码保存后，网页会自动进行刷新，启动新代码。

②热模块更换这里也会有bug存在，这和所用的浏览器也会有关，例如有时候刷新页面，会发现代码还是旧的，这点IE11时常会出现该bug。另外关于热模块更换的详细知识会在以后的Webpack编译篇讲解。

③官方推荐的npm start指令所对应的server就是以nodejs+express起的，详细可看以下代码：

 'use strict';

 /* eslint func-names: off */
 require('./polyfills');

 const fs = require('fs');
 const http = require('http');
 const path = require('path');
 const url = require('url');
 const chokidar = require('chokidar');
 const compress = require('compression');
 const del = require('del');
 const express = require('express');
 const httpProxyMiddleware = require('http-proxy-middleware');
 const ip = require('ip');
 const killable = require('killable');
 const serveIndex = require('serve-index');
 const historyApiFallback = require('connect-history-api-fallback');
 const selfsigned = require('selfsigned');
 const sockjs = require('sockjs');
 const spdy = require('spdy');
 const webpack = require('webpack');
 const webpackDevMiddleware = require('webpack-dev-middleware');
 const OptionsValidationError = require('./OptionsValidationError');
 const optionsSchema = require('./optionsSchema.json');

 const clientStats = { errorDetails: false };
 const log = console.log; // eslint-disable-line no-console

 function Server(compiler, options) {
   // Default options
   if (!options) options = {};

   const validationErrors = webpack.validateSchema(optionsSchema, options);
   if (validationErrors.length) {
     throw new OptionsValidationError(validationErrors);
   }

   if (options.lazy && !options.filename) {
     throw new Error("'filename' option must be set in lazy mode.");
   }

   this.hot = options.hot || options.hotOnly;
   this.headers = options.headers;
   this.clientLogLevel = options.clientLogLevel;
   this.clientOverlay = options.overlay;
   this.progress = options.progress;
   this.disableHostCheck = !!options.disableHostCheck;
   this.publicHost = options.public;
   this.allowedHosts = options.allowedHosts;
   this.sockets = [];
   this.contentBaseWatchers = [];

   // Listening for events
   const invalidPlugin = () => {
     this.sockWrite(this.sockets, 'invalid');
   };
   if (this.progress) {
     const progressPlugin = new webpack.ProgressPlugin((percent, msg, addInfo) => {
       percent = Math.floor(percent * 100);
       if (percent === 100) msg = 'Compilation completed';
       if (addInfo) msg = `${msg} (${addInfo})`;
       this.sockWrite(this.sockets, 'progress-update', { percent, msg });
     });
     compiler.apply(progressPlugin);
   }
   compiler.plugin('compile', invalidPlugin);
   compiler.plugin('invalid', invalidPlugin);
   compiler.plugin('done', (stats) => {
     this._sendStats(this.sockets, stats.toJson(clientStats));
     this._stats = stats;
   });

   // Init express server
   const app = this.app = new express(); // eslint-disable-line

   app.all('*', (req, res, next) => { // eslint-disable-line
     if (this.checkHost(req.headers)) { return next(); }
     res.send('Invalid Host header');
   });

   // middleware for serving webpack bundle
   this.middleware = webpackDevMiddleware(compiler, options);

   app.get('/__webpack_dev_server__/live.bundle.js', (req, res) => {
     res.setHeader('Content-Type', 'application/javascript');
     fs.createReadStream(path.join(__dirname, '..', 'client', 'live.bundle.js')).pipe(res);
   });

   app.get('/__webpack_dev_server__/sockjs.bundle.js', (req, res) => {
     res.setHeader('Content-Type', 'application/javascript');
     fs.createReadStream(path.join(__dirname, '..', 'client', 'sockjs.bundle.js')).pipe(res);
   });

   app.get('/webpack-dev-server.js', (req, res) => {
     res.setHeader('Content-Type', 'application/javascript');
     fs.createReadStream(path.join(__dirname, '..', 'client', 'index.bundle.js')).pipe(res);
   });

   app.get('/webpack-dev-server/*', (req, res) => {
     res.setHeader('Content-Type', 'text/html');
     fs.createReadStream(path.join(__dirname, '..', 'client', 'live.html')).pipe(res);
   });

   app.get('/webpack-dev-server', (req, res) => {
     res.setHeader('Content-Type', 'text/html');
     res.write('<!DOCTYPE html><html><head><meta charset="utf-8"/></head><body>');
     const outputPath = this.middleware.getFilenameFromUrl(options.publicPath || '/');
     const filesystem = this.middleware.fileSystem;

     function writeDirectory(baseUrl, basePath) {
       const content = filesystem.readdirSync(basePath);
       res.write('<ul>');
       content.forEach((item) => {
         const p = `${basePath}/${item}`;
         if (filesystem.statSync(p).isFile()) {
           res.write('<li><a href="');
           res.write(baseUrl + item);
           res.write('">');
           res.write(item);
           res.write('</a></li>');
           if (/\.js$/.test(item)) {
             const htmlItem = item.substr(0, item.length - 3);
             res.write('<li><a href="');
             res.write(baseUrl + htmlItem);
             res.write('">');
             res.write(htmlItem);
             res.write('</a> (magic html for ');
             res.write(item);
             res.write(') (<a href="');
             res.write(baseUrl.replace(/(^(https?:\/\/[^\/]+)?\/)/, "$1webpack-dev-server/") + htmlItem); // eslint-disable-line
             res.write('">webpack-dev-server</a>)</li>');
           }
         } else {
           res.write('<li>');
           res.write(item);
           res.write('<br>');
           writeDirectory(`${baseUrl + item}/`, p);
           res.write('</li>');
         }
       });
       res.write('</ul>');
     }
     writeDirectory(options.publicPath || '/', outputPath);
     res.end('</body></html>');
   });

   let contentBase;
   if (options.contentBase !== undefined) { // eslint-disable-line
     contentBase = options.contentBase; // eslint-disable-line
   } else {
     contentBase = process.cwd();
   }

   // Keep track of websocket proxies for external websocket upgrade.
   const websocketProxies = [];

   const features = {
     compress() {
       if (options.compress) {
         // Enable gzip compression.
         app.use(compress());
       }
     },

     proxy() {
       if (options.proxy) {
         /**
           * Assume a proxy configuration specified as:
           * proxy: {
           *   'context': { options }
           * }
           * OR
           * proxy: {
           *   'context': 'target'
           * }
           */
         if (!Array.isArray(options.proxy)) {
           options.proxy = Object.keys(options.proxy).map((context) => {
             let proxyOptions;
             // For backwards compatibility reasons.
             const correctedContext = context.replace(/^\*$/, '**').replace(/\/\*$/, '');

             if (typeof options.proxy[context] === 'string') {
               proxyOptions = {
                 context: correctedContext,
                 target: options.proxy[context]
               };
             } else {
               proxyOptions = Object.assign({}, options.proxy[context]);
               proxyOptions.context = correctedContext;
             }
             proxyOptions.logLevel = proxyOptions.logLevel || 'warn';

             return proxyOptions;
           });
         }

         const getProxyMiddleware = (proxyConfig) => {
           const context = proxyConfig.context || proxyConfig.path;

           // It is possible to use the `bypass` method without a `target`.
           // However, the proxy middleware has no use in this case, and will fail to instantiate.
           if (proxyConfig.target) {
             return httpProxyMiddleware(context, proxyConfig);
           }
         };

         /**
         * Assume a proxy configuration specified as:
         * proxy: [
         *   {
         *     context: ...,
         *     ...options...
         *   },
         *   // or:
         *   function() {
         *     return {
         *       context: ...,
         *       ...options...
         *     };
         *   }
         * ]
         */
         options.proxy.forEach((proxyConfigOrCallback) => {
           let proxyConfig;
           let proxyMiddleware;

           if (typeof proxyConfigOrCallback === 'function') {
             proxyConfig = proxyConfigOrCallback();
           } else {
             proxyConfig = proxyConfigOrCallback;
           }

           proxyMiddleware = getProxyMiddleware(proxyConfig);
           if (proxyConfig.ws) {
             websocketProxies.push(proxyMiddleware);
           }

           app.use((req, res, next) => {
             if (typeof proxyConfigOrCallback === 'function') {
               const newProxyConfig = proxyConfigOrCallback();
               if (newProxyConfig !== proxyConfig) {
                 proxyConfig = newProxyConfig;
                 proxyMiddleware = getProxyMiddleware(proxyConfig);
               }
             }
             const bypass = typeof proxyConfig.bypass === 'function';
             // eslint-disable-next-line
             const bypassUrl = bypass && proxyConfig.bypass(req, res, proxyConfig) || false;

             if (bypassUrl) {
               req.url = bypassUrl;
               next();
             } else if (proxyMiddleware) {
               return proxyMiddleware(req, res, next);
             } else {
               next();
             }
           });
         });
       }
     },

     historyApiFallback() {
       if (options.historyApiFallback) {
         // Fall back to /index.html if nothing else matches.
         app.use(historyApiFallback(typeof options.historyApiFallback === 'object' ? options.historyApiFallback : null));
       }
     },

     contentBaseFiles() {
       if (Array.isArray(contentBase)) {
         contentBase.forEach((item) => {
           app.get('*', express.static(item));
         });
       } else if (/^(https?:)?\/\//.test(contentBase)) {
         log('Using a URL as contentBase is deprecated and will be removed in the next major version. Please use the proxy option instead.');
         log('proxy: {\n\t"*": "<your current contentBase configuration>"\n}'); // eslint-disable-line quotes
         // Redirect every request to contentBase
         app.get('*', (req, res) => {
           res.writeHead(302, {
             Location: contentBase + req.path + (req._parsedUrl.search || '')
           });
           res.end();
         });
       } else if (typeof contentBase === 'number') {
         log('Using a number as contentBase is deprecated and will be removed in the next major version. Please use the proxy option instead.');
         log('proxy: {\n\t"*": "//localhost:<your current contentBase configuration>"\n}'); // eslint-disable-line quotes
         // Redirect every request to the port contentBase
         app.get('*', (req, res) => {
           res.writeHead(302, {
             Location: `//localhost:${contentBase}${req.path}${req._parsedUrl.search || ''}`
           });
           res.end();
         });
       } else {
         // route content request
         app.get('*', express.static(contentBase, options.staticOptions));
       }
     },

     contentBaseIndex() {
       if (Array.isArray(contentBase)) {
         contentBase.forEach((item) => {
           app.get('*', serveIndex(item));
         });
       } else if (!/^(https?:)?\/\//.test(contentBase) && typeof contentBase !== 'number') {
         app.get('*', serveIndex(contentBase));
       }
     },

     watchContentBase: () => {
       if (/^(https?:)?\/\//.test(contentBase) || typeof contentBase === 'number') {
         throw new Error('Watching remote files is not supported.');
       } else if (Array.isArray(contentBase)) {
         contentBase.forEach((item) => {
           this._watch(item);
         });
       } else {
         this._watch(contentBase);
       }
     },

     before: () => {
       if (typeof options.before === 'function') { options.before(app, this); }
     },

     middleware: () => {
       // include our middleware to ensure it is able to handle '/index.html' request after redirect
       app.use(this.middleware);
     },

     after: () => {
       if (typeof options.after === 'function') { options.after(app, this); }
     },

     headers: () => {
       app.all('*', this.setContentHeaders.bind(this));
     },

     magicHtml: () => {
       app.get('*', this.serveMagicHtml.bind(this));
     },

     setup: () => {
       if (typeof options.setup === 'function') {
         log('The `setup` option is deprecated and will be removed in v3. Please update your config to use `before`');
         options.setup(app, this);
       }
     }
   };

   const defaultFeatures = ['before', 'setup', 'headers', 'middleware'];
   if (options.proxy) { defaultFeatures.push('proxy', 'middleware'); }
   if (contentBase !== false) { defaultFeatures.push('contentBaseFiles'); }
   if (options.watchContentBase) { defaultFeatures.push('watchContentBase'); }
   if (options.historyApiFallback) {
     defaultFeatures.push('historyApiFallback', 'middleware');
     if (contentBase !== false) { defaultFeatures.push('contentBaseFiles'); }
   }
   defaultFeatures.push('magicHtml');
   if (contentBase !== false) { defaultFeatures.push('contentBaseIndex'); }
   // compress is placed last and uses unshift so that it will be the first middleware used
   if (options.compress) { defaultFeatures.unshift('compress'); }
   if (options.after) { defaultFeatures.push('after'); }

   (options.features || defaultFeatures).forEach((feature) => {
     features[feature]();
   });

   if (options.https) {
     // for keep supporting CLI parameters
     if (typeof options.https === 'boolean') {
       options.https = {
         key: options.key,
         cert: options.cert,
         ca: options.ca,
         pfx: options.pfx,
         passphrase: options.pfxPassphrase,
         requestCert: options.requestCert || false
       };
     }

     let fakeCert;
     if (!options.https.key || !options.https.cert) {
       // Use a self-signed certificate if no certificate was configured.
       // Cycle certs every 24 hours
       const certPath = path.join(__dirname, '../ssl/server.pem');
       let certExists = fs.existsSync(certPath);

       if (certExists) {
         const certStat = fs.statSync(certPath);
         const certTtl = 1000 * 60 * 60 * 24;
         const now = new Date();

         // cert is more than 30 days old, kill it with fire
         if ((now - certStat.ctime) / certTtl > 30) {
           log('SSL Certificate is more than 30 days old. Removing.');
           del.sync([certPath], { force: true });
           certExists = false;
         }
       }

       if (!certExists) {
         log('Generating SSL Certificate');
         const attrs = [{ name: 'commonName', value: 'localhost' }];
         const pems = selfsigned.generate(attrs, {
           algorithm: 'sha256',
           days: 30,
           keySize: 2048,
           extensions: [{
             name: 'basicConstraints',
             cA: true
           }, {
             name: 'keyUsage',
             keyCertSign: true,
             digitalSignature: true,
             nonRepudiation: true,
             keyEncipherment: true,
             dataEncipherment: true
           }, {
             name: 'subjectAltName',
             altNames: [
               {
                 // type 2 is DNS
                 type: 2,
                 value: 'localhost'
               },
               {
                 type: 2,
                 value: 'localhost.localdomain'
               },
               {
                 type: 2,
                 value: 'lvh.me'
               },
               {
                 type: 2,
                 value: '*.lvh.me'
               },
               {
                 type: 2,
                 value: '[::1]'
               },
               {
                 // type 7 is IP
                 type: 7,
                 ip: '127.0.0.1'
               },
               {
                 type: 7,
                 ip: 'fe80::1'
               }
             ]
           }]
         });

         fs.writeFileSync(certPath, pems.private + pems.cert, { encoding: 'utf-8' });
       }
       fakeCert = fs.readFileSync(certPath);
     }

     options.https.key = options.https.key || fakeCert;
     options.https.cert = options.https.cert || fakeCert;

     if (!options.https.spdy) {
       options.https.spdy = {
         protocols: ['h2', 'http/1.1']
       };
     }

     this.listeningApp = spdy.createServer(options.https, app);
   } else {
     this.listeningApp = http.createServer(app);
   }

   killable(this.listeningApp);

   // Proxy websockets without the initial http request
   // https://github.com/chimurai/http-proxy-middleware#external-websocket-upgrade
   websocketProxies.forEach(function (wsProxy) {
     this.listeningApp.on('upgrade', wsProxy.upgrade);
   }, this);
 }

 Server.prototype.use = function () {
   // eslint-disable-next-line
   this.app.use.apply(this.app, arguments);
 };

 Server.prototype.setContentHeaders = function (req, res, next) {
   if (this.headers) {
     for (const name in this.headers) { // eslint-disable-line
       res.setHeader(name, this.headers[name]);
     }
   }

   next();
 };

 Server.prototype.checkHost = function (headers) {
   // allow user to opt-out this security check, at own risk
   if (this.disableHostCheck) return true;

   // get the Host header and extract hostname
   // we don't care about port not matching
   const hostHeader = headers.host;
   if (!hostHeader) return false;

   // use the node url-parser to retrieve the hostname from the host-header.
   const hostname = url.parse(`//${hostHeader}`, false, true).hostname;

   // always allow requests with explicit IPv4 or IPv6-address.
   // A note on IPv6 addresses: hostHeader will always contain the brackets denoting
   // an IPv6-address in URLs, these are removed from the hostname in url.parse(),
   // so we have the pure IPv6-address in hostname.
   if (ip.isV4Format(hostname) || ip.isV6Format(hostname)) return true;

   // always allow localhost host, for convience
   if (hostname === 'localhost') return true;

   // allow if hostname is in allowedHosts
   if (this.allowedHosts && this.allowedHosts.length) {
     for (let hostIdx = 0; hostIdx < this.allowedHosts.length; hostIdx++) {
       const allowedHost = this.allowedHosts[hostIdx];
       if (allowedHost === hostname) return true;

       // support "." as a subdomain wildcard
       // e.g. ".example.com" will allow "example.com", "www.example.com", "subdomain.example.com", etc
       if (allowedHost[0] === '.') {
         // "example.com"
         if (hostname === allowedHost.substring(1)) return true;
         // "*.example.com"
         if (hostname.endsWith(allowedHost)) return true;
       }
     }
   }

   // allow hostname of listening adress
   if (hostname === this.listenHostname) return true;

   // also allow public hostname if provided
   if (typeof this.publicHost === 'string') {
     const idxPublic = this.publicHost.indexOf(':');
     const publicHostname = idxPublic >= 0 ? this.publicHost.substr(0, idxPublic) : this.publicHost;
     if (hostname === publicHostname) return true;
   }

   // disallow
   return false;
 };

 // delegate listen call and init sockjs
 Server.prototype.listen = function (port, hostname, fn) {
   this.listenHostname = hostname;
   // eslint-disable-next-line

   const returnValue = this.listeningApp.listen(port, hostname, (err) => {
     const sockServer = sockjs.createServer({
       // Use provided up-to-date sockjs-client
       sockjs_url: '/__webpack_dev_server__/sockjs.bundle.js',
       // Limit useless logs
       log(severity, line) {
         if (severity === 'error') {
           log(line);
         }
       }
     });

     sockServer.on('connection', (conn) => {
       if (!conn) return;
       if (!this.checkHost(conn.headers)) {
         this.sockWrite([conn], 'error', 'Invalid Host header');
         conn.close();
         return;
       }
       this.sockets.push(conn);

       conn.on('close', () => {
         const connIndex = this.sockets.indexOf(conn);
         if (connIndex >= 0) {
           this.sockets.splice(connIndex, 1);
         }
       });

       if (this.clientLogLevel) { this.sockWrite([conn], 'log-level', this.clientLogLevel); }

       if (this.progress) { this.sockWrite([conn], 'progress', this.progress); }

       if (this.clientOverlay) { this.sockWrite([conn], 'overlay', this.clientOverlay); }

       if (this.hot) this.sockWrite([conn], 'hot');

       if (!this._stats) return;
       this._sendStats([conn], this._stats.toJson(clientStats), true);
     });

     sockServer.installHandlers(this.listeningApp, {
       prefix: '/sockjs-node'
     });

     if (fn) {
       fn.call(this.listeningApp, err);
     }
   });

   return returnValue;
 };

 Server.prototype.close = function (callback) {
   this.sockets.forEach((sock) => {
     sock.close();
   });
   this.sockets = [];

   this.contentBaseWatchers.forEach((watcher) => {
     watcher.close();
   });
   this.contentBaseWatchers = [];

   this.listeningApp.kill(() => {
     this.middleware.close(callback);
   });
 };

 Server.prototype.sockWrite = function (sockets, type, data) {
   sockets.forEach((sock) => {
     sock.write(JSON.stringify({
       type,
       data
     }));
   });
 };

 Server.prototype.serveMagicHtml = function (req, res, next) {
   const _path = req.path;
   try {
     if (!this.middleware.fileSystem.statSync(this.middleware.getFilenameFromUrl(`${_path}.js`)).isFile()) { return next(); }
     // Serve a page that executes the javascript
     res.write('<!DOCTYPE html><html><head><meta charset="utf-8"/></head><body><script type="text/javascript" charset="utf-8" src="');
     res.write(_path);
     res.write('.js');
     res.write(req._parsedUrl.search || '');
     res.end('"></script></body></html>');
   } catch (e) {
     return next();
   }
 };

 // send stats to a socket or multiple sockets
 Server.prototype._sendStats = function (sockets, stats, force) {
   if (!force &&
   stats &&
   (!stats.errors || stats.errors.length === 0) &&
   stats.assets &&
   stats.assets.every(asset => !asset.emitted)
   ) { return this.sockWrite(sockets, 'still-ok'); }
   this.sockWrite(sockets, 'hash', stats.hash);
   if (stats.errors.length > 0) { this.sockWrite(sockets, 'errors', stats.errors); } else if (stats.warnings.length > 0) { this.sockWrite(sockets, 'warnings', stats.warnings); } else { this.sockWrite(sockets, 'ok'); }
 };

 Server.prototype._watch = function (watchPath) {
   const watcher = chokidar.watch(watchPath).on('change', () => {
     this.sockWrite(this.sockets, 'content-changed');
   });

   this.contentBaseWatchers.push(watcher);
 };

 Server.prototype.invalidate = function () {
   if (this.middleware) this.middleware.invalidate();
 };

 // Export this logic, so that other implementations, like task-runners can use it
 Server.addDevServerEntrypoints = require('./util/addDevServerEntrypoints');

 module.exports = Server;

我们可以关注代码中的这两句话，再看看代码上下部分，想必大家也能了解了：

......

const express = require('express');   

......

const app = this.app = new express(); // eslint-disable-line

......

④：那么要当做产品发布的话也用npm start么？ NO NO NO， 详细可看我们的第三大步

---

3.架设服务的话就需要编译发布代码，此时需要做以下行为：

①cmd下输入以下指令：npm run build （run build的定义在package.json里，调用的是webpack.config.prod.js）

②编译完成后，本地会出现build文件夹，如图

③这里不用推荐的npm install -g serve的模块做server，这样之后弄不了反向代理。这里推荐用node+express来写一个简单的server，新建一个文件，命名为server,js，代码如下，将其保存于build目录下（本地注了释反向代理设置，如果需要去掉注释即可，端口可自行设置）：

const express = require('express')
const proxy = require('http-proxy-middleware')

/*const options = {
    target: "http://localhost:8080",
    changeOrigin:true,
}

const apiProxy = proxy(options)*/

const app = express()

app.use(express.static(__dirname))
//app.use('/', apiProxy)
app.listen(80)

④cd进build目录，执行指令node server.js， 打开浏览器输入localhost:80就可看到成果了

关于后台搭建请见“后台springboot分类”里的springboot框架搭建，React第二章也已发布