一篇文章构建你的 NodeJS 知识体系(W字长文)

# 使用 nvm 安装
https://github.com/creationix/nvm#install-script # Git install

nvm install
nvm alias default

# 卸载 pkg 安装版
sudo rm -rf /usr/local/{bin/{node,npm},lib/node_modules/npm,lib/node,share/man/*/node.*}

// 通过如下模块包装得到
(funciton (exports, require, module, __filename, __dirname) { // 包装头

}); // 包装尾

(funciton(exports, require, module, __filename, __dirname) { // 包装头
  console.log('hello world!') // 原始文件
}); // 包装尾

// module-2.js
exports.method = function() {
  return 'Hello';
};

exports.method2 = function() {
  return 'Hello again';
};

// module-1.js
const module2 = require('./module-2');
console.log(module2.method()); // Hello
console.log(module2.method2()); // Hello again

console.log('__dirname:', __dirname); // 文件夹
console.log('__filename:', __filename); // 文件
path.join(__dirname, 'views', 'view.html'); // 如果不希望自己手动处理 / 的问题，使用 path.join

node
console.log(process.env.PATH.split(':').join('\n'));

process.env.PATH += ':/a_new_path_to_executables';

// 获取平台信息
process.arch // x64
process.platform // darwin

// 获取内存使用情况
process.memoryUsage();

// 获取命令行参数
process.argv

const EventEmitter = require('events').EventEmitter;

function complexOperations() {
  const events = new EventEmitter();

  process.nextTick(function () {
    events.emit('success');
  });

  return events;
}

complexOperations().on('success', function () {
  console.log('success!');
});

// 生成 data URI
const fs = require('fs');
const mime = 'image/png';
const encoding = 'base64';
const base64Data = fs.readFileSync(`${__dirname}/monkey.png`).toString(encoding);
const uri = `data:${mime};${encoding},${base64Data}`;
console.log(uri);

// data URI 转文件
const fs = require('fs');
const uri = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgA...';
const base64Data = uri.split(',')[1];
const buf = Buffer(base64Data, 'base64');
fs.writeFileSync(`${__dirname}/secondmonkey.png`, buf);

const EventEmitter = require('events').EventEmitter;

const AudioDevice = {
  play: function (track) {
    console.log('play', track);
  },
  stop: function () {
    console.log('stop');
  },
};

class MusicPlayer extends EventEmitter {
  constructor() {
    super();
    this.playing = false;
  }
}

const musicPlayer = new MusicPlayer();
musicPlayer.on('play', function (track) {
  this.playing = true;
  AudioDevice.play(track);
});
musicPlayer.on('stop', function () {
  this.playing = false;
  AudioDevice.stop();
});

musicPlayer.emit('play', 'The Roots - The Fire');
setTimeout(function () {
  musicPlayer.emit('stop');
}, 1000);

// 处理异常
// EventEmitter 实例发生错误会发出一个 error 事件
// 如果没有监听器，默认动作是打印一个堆栈并退出程序
musicPlayer.on('error', function (err) {
  console.err('Error:', err);
});

const util = require('util');
const fs = require('fs');
const readAsync = util.promisify(fs.readFile);

async function init() {
  try {
    let data = await readAsync('./package.json');

    data  =JSON.parse(data);

    console.log(data.name);
  } catch (err) {
    console.log(err);
  }
}

const http = require('http');
const fs = require('fs');

http.createServer((req, res) => {
  fs.readFile(`${__dirname}/index.html`, (err, data) => {
    if (err) {
      res.statusCode = 500;
      res.end(String(err));
      return;
    }

    res.end(data);
  });
}).listen(8000);

const http = require('http');
const fs = require('fs');

http.createServer((req, res) => {
  fs.createReadStream(`${__dirname}/index.html`).pipe(res);
}).listen(8000);

const http = require('http');
const fs = require('fs');
const zlib = require('zlib');

http.createServer((req, res) => {
  res.writeHead(200, {
    'content-encoding': 'gzip',
  });
  fs.createReadStream(`${__dirname}/index.html`)
    .pipe(zlib.createGzip())
    .pipe(res);
}).listen(8000)

const fs = require('fs');
const stream = fs.createReadStream('not-found');

stream.on('error', (err) => {
  console.trace();
  console.error('Stack:', err.stack);
  console.error('The error raised was:', err);
});

{ "position": 0, "letter": "a" }
{ "position": 1, "letter": "b" }
{ "position": 2, "letter": "c" }
{ "position": 3, "letter": "d" }
{ "position": 4, "letter": "e" }
{ "position": 5, "letter": "f" }
{ "position": 6, "letter": "g" }
{ "position": 7, "letter": "h" }
{ "position": 8, "letter": "i" }
{ "position": 9, "letter": "j" }

const stream = require('stream');
const fs = require('fs');
const util = require('util');

class JSONLineReader extends stream.Readable {
  constructor(source) {
    super();
    this._source = source;
    this._foundLineEnd = false;
    this._buffer = '';

    source.on('readable', () => {
      this.read();
    });
  }

  // 所有定制 stream.Readable 类都需要实现 _read 方法
  _read(size) {
    let chunk;
    let line;
    let result;

    if (this._buffer.length === 0) {
      chunk = this._source.read();
      this._buffer += chunk;
    }

    const lineIndex = this._buffer.indexOf('\n');

    if (lineIndex !== -1) {
      line = this._buffer.slice(0, lineIndex); // 从 buffer 的开始截取第一行来获取一些文本进行解析
      if (line) {
        result = JSON.parse(line);
        this._buffer = this._buffer.slice(lineIndex + 1);
        this.emit('object', result); // 当一个 JSON 记录解析出来的时候，触发一个 object 事件
        this.push(util.inspect(result)); // 将解析好的 SJON 发回内部队列
      } else {
        this._buffer = this._buffer.slice(1);
      }
    }
  }
}

const input = fs.createReadStream(`${__dirname}/json-lines.txt`, {
  encoding: 'utf8',
});
const jsonLineReader = new JSONLineReader(input); // 创建一个 JSONLineReader 实例，传递一个文件流给它处理

jsonLineReader.on('object', (obj) => {
  console.log('pos:', obj.position, '- letter:', obj.letter);
});

cat json-lines.txt | node stram_writable.js

const stream = require('stream');

class GreenStream extends stream.Writable {
  constructor(options) {
    super(options);
  }

  _write(chunk, encoding, cb) {
    process.stdout.write(`\u001b[32m${chunk}\u001b[39m`);
    cb();
  }
}

process.stdin.pipe(new GreenStream());

const assert = require('assert');
const fs = require('fs');
const CSVParser = require('./csvparser');

const parser = new CSVParser();
const actual = [];

fs.createReadStream(`${__dirname}/sample.csv`)
  .pipe(parser);

process.on('exit', function () {
  actual.push(parser.read());
  actual.push(parser.read());
  actual.push(parser.read());

  const expected = [
    { name: 'Alex', location: 'UK', role: 'admin' },
    { name: 'Sam', location: 'France', role: 'user' },
    { name: 'John', location: 'Canada', role: 'user' },
  ];

  assert.deepEqual(expected, actual);
});

const fs = require('fs');
const assert = require('assert');

const fd = fs.openSync('./file.txt', 'w+');
const writeBuf = new Buffer('some data to write');
fs.writeSync(fd, writeBuf, 0, writeBuf.length, 0);

const readBuf = new Buffer(writeBuf.length);
fs.readSync(fd, readBuf, 0, writeBuf.length, 0);
assert.equal(writeBuf.toString(), readBuf.toString());

fs.closeSync(fd);

const fs = require('fs');
const readable = fs.createReadStream('./original.txt');
const writeable = fs.createWriteStream('./copy.txt');
readable.pipe(writeable);

const fs = require('fs');
const config = JSON.parse(fs.readFileSync('./config.json').toString());
init(config);

const config = require('./config.json);
init(config);

const fd = fs.openSync('myfile', 'a');
console.log(typeof fd === 'number'); // true

// 所有需要打开文件的方法，fs.writeFile、fs.createWriteStream、fs.open 都有一个 x 标记
// 这个文件应该已独占打开，若这个文件存在，文件不能被打开
fs.open('config.lock', 'wx', (err) => {
  if (err) { return console.err(err); }
});

// 最好将当前进程号写进文件锁中
// 当有异常的时候就知道最后这个锁的进程
fs.writeFile(
  'config.lock',
  process.pid,
  { flogs: 'wx' },
  (err) => {
    if (err) { return console.error(err) };
  },
);

fs.mkidr('config.lock', (err) => {
  if (err) { return console.error(err); }
  fs.writeFile(`/config.lock/${process.pid}`, (err) => {
    if (err) { return console.error(err); }
  });
});

const fs = require('fs');
const lockDir = 'config.lock';
let hasLock = false;

exports.lock = function (cb) { // 获取锁
  if (hasLock) { return cb(); } // 已经获取了一个锁
  fs.mkdir(lockDir, function (err) {
    if (err) { return cb(err); } // 无法创建锁

    fs.writeFile(lockDir + '/' + process.pid, function (err) { // 把 PID写入到目录中以便调试
      if (err) { console.error(err); } // 无法写入 PID，继续运行
      hasLock = true; // 锁创建了
      return cb();
    });
  });
};

exports.unlock = function (cb) { // 解锁方法
  if (!hasLock) { return cb(); } // 如果没有需要解开的锁
  fs.unlink(lockDir + '/' + process.pid, function (err) {
    if (err) { return cb(err); }

    fs.rmdir(lockDir, function (err) {
      if (err) return cb(err);
      hasLock = false;
      cb();
    });
  });
};

process.on('exit', function () {
  if (hasLock) {
    fs.unlinkSync(lockDir + '/' + process.pid); // 如果还有锁，在退出之前同步删除掉
    fs.rmdirSync(lockDir);
    console.log('removed lock');
  }
});

dir-a
├── dir-b
│   ├── dir-c
│   │   ├── dir-d
│   │   │   └── file-e.png
│   │   └── file-e.png
│   ├── file-c.js
│   └── file-d.txt
├── file-a.js
└── file-b.txt

[
  'dir-a/dir-b/dir-c/dir-d/file-e.png',
  'dir-a/dir-b/dir-c/file-e.png',
  'dir-a/dir-b/file-c.js',
  'dir-a/dir-b/file-d.txt',
  'dir-a/file-a.js',
  'dir-a/file-b.txt',
]

const fs = require('fs');
const join = require('path').join;

// 同步查找
exports.findSync = function (nameRe, startPath) {
  const results = [];

  function finder(path) {
    const files = fs.readdirSync(path);

    for (let i = 0; i < files.length; i++) {
      const fpath = join(path, files[i]);
      const stats = fs.statSync(fpath);

      if (stats.isDirectory()) { finder(fpath); }

      if (stats.isFile() && nameRe.test(files[i])) {
        results.push(fpath);
      }
    }
  }

  finder(startPath);
  return results;
};

// 异步查找
exports.find = function (nameRe, startPath, cb) { // cb 可以传入 console.log，灵活
  const results = [];
  let asyncOps = 0; // 2

  function finder(path) {
    asyncOps++;
    fs.readdir(path, function (er, files) {
      if (er) { return cb(er); }

      files.forEach(function (file) {
        const fpath = join(path, file);

        asyncOps++;
        fs.stat(fpath, function (er, stats) {
          if (er) { return cb(er); }

          if (stats.isDirectory()) finder(fpath);

          if (stats.isFile() && nameRe.test(file)) {
            results.push(fpath);
          }

          asyncOps--;
          if (asyncOps == 0) {
            cb(null, results);
          }
        });
      });

      asyncOps--;
      if (asyncOps == 0) {
        cb(null, results);
      }
    });
  }

  finder(startPath);
};

console.log(exports.findSync(/file.*/, `${__dirname}/dir-a`));
console.log(exports.find(/file.*/, `${__dirname}/dir-a`, console.log));

const fs = require('fs');
fs.watch('./watchdir', console.log); // 稳定且快
fs.watchFile('./watchdir', console.log); // 跨平台

const fs = require('fs');
const readline = require('readline');

const rl = readline.createInterface({
  input: fs.createReadStream('/etc/hosts'),
  crlfDelay: Infinity
});

rl.on('line', (line) => {
  console.log(`cc ${line}`);
  const extract = line.match(/(\d+\.\d+\.\d+\.\d+) (.*)/);
});

function get_local_ip() {
  const interfaces = require('os').networkInterfaces();
  let IPAdress = '';
  for (const devName in interfaces) {
    const iface = interfaces[devName];
    for (let i = 0; i < iface.length; i++) {
      const alias = iface[i];
      if (alias.family === 'IPv4' && alias.address !== '127.0.0.1' && !alias.internal) {
        IPAdress = alias.address;
      }
    }
  }
  return IPAdress;
}

const assert = require('assert');
const net = require('net');
let clients = 0;
let expectedAssertions = 2;

const server = net.createServer(function (client) {
  clients++;
  const clientId = clients;
  console.log('Client connected:', clientId);

  client.on('end', function () {
    console.log('Client disconnected:', clientId);
  });

  client.write('Welcome client: ' + clientId);
  client.pipe(client);
});

server.listen(8000, function () {
  console.log('Server started on port 8000');

  runTest(1, function () {
    runTest(2, function () {
      console.log('Tests finished');
      assert.equal(0, expectedAssertions);
      server.close();
    });
  });
});

function runTest(expectedId, done) {
  const client = net.connect(8000);

  client.on('data', function (data) {
    const expected = 'Welcome client: ' + expectedId;
    assert.equal(data.toString(), expected);
    expectedAssertions--;
    client.end();
  });

  client.on('end', done);
}

const dgram = require('dgram');
const fs = require('fs');
const port = 41230;
const defaultSize = 16;

function Client(remoteIP) {
  const inStream = fs.createReadStream(__filename); // 从当前文件创建可读流
  const socket = dgram.createSocket('udp4'); // 创建新的数据流 socket 作为客户端

  inStream.on('readable', function () {
    sendData(); // 当可读流准备好，开始发送数据到服务器
  });

  function sendData() {
    const message = inStream.read(defaultSize); // 读取数据块

    if (!message) {
      return socket.unref(); // 客户端完成任务后，使用 unref 安全关闭它
    }

    // 发送数据到服务器
    socket.send(message, 0, message.length, port, remoteIP, function () {
        sendData();
      }
    );
  }
}

function Server() {
  const socket = dgram.createSocket('udp4'); // 创建一个 socket 提供服务

  socket.on('message', function (msg) {
    process.stdout.write(msg.toString());
  });

  socket.on('listening', function () {
    console.log('Server ready:', socket.address());
  });

  socket.bind(port);
}

if (process.argv[2] === 'client') { // 根据命令行选项确定运行客户端还是服务端
  new Client(process.argv[3]);
} else {
  new Server();
}

const assert = require('assert');
const http = require('http');

const server = http.createServer(function(req, res) {
  res.writeHead(200, { 'Content-Type': 'text/plain' }); // 写入基于文本的响应头
  res.write('Hello, world.'); // 发送消息回客户端
  res.end();
});

server.listen(8000, function() {
  console.log('Listening on port 8000');
});

const req = http.request({ port: 8000}, function(res) { // 创建请求
  console.log('HTTP headers:', res.headers);
  res.on('data', function(data) { // 给 data 事件创建监听，确保和期望值一致
    console.log('Body:', data.toString());
    assert.equal('Hello, world.', data.toString());
    assert.equal(200, res.statusCode);
    server.unref();
    console.log('测试完成');
  });
});

req.end();

const http = require('http');
const https = require('https');
const url = require('url'); // 有很多接续 URLs 的方法

// 构造函数被用来创建一个对象来构成请求对象的声明周期
function Request() {
  this.maxRedirects = 10;
  this.redirects = 0;
}

Request.prototype.get = function(href, callback) {
  const uri = url.parse(href); // 解析 URLs 成为 Node http 模块使用的格式，确定是否使用 HTTPS
  const options = { host: uri.host, path: uri.path };
  const httpGet = uri.protocol === 'http:' ? http.get : https.get;

  console.log('GET:', href);

  function processResponse(response) {
    if (response.statusCode >= 300 && response.statusCode < 400) { // 检查状态码是否在 HTTP 重定向范围
      if (this.redirects >= this.maxRedirects) {
        this.error = new Error('Too many redirects for: ' + href);
      } else {
        this.redirects++; // 重定向计数自增
        href = url.resolve(options.host, response.headers.location); // 使用 url.resolve 确保相对路径的 URLs 转换为绝对路径 URLs
        return this.get(href, callback);
      }
    }

    response.url = href;
    response.redirects = this.redirects;

    console.log('Redirected:', href);

    function end() {
      console.log('Connection ended');
      callback(this.error, response);
    }

    response.on('data', function(data) {
      console.log('Got data, length:', data.length);
    });

    response.on('end', end.bind(this)); // 绑定回调到 Request 实例，确保能拿到实例属性
  }

  httpGet(options, processResponse.bind(this))
    .on('error', function(err) {
      callback(err);
    });
};

const request = new Request();
request.get('http://google.com/', function(err, res) {
  if (err) {
    console.error(err);
  } else {
    console.log(`
      Fetched URL: ${res.url} with ${res.redirects} redirects
    `);
    process.exit();
  }
});

const http = require('http');
const url = require('url');

http.createServer(function(req, res) {
  console.log('start request:', req.url);
  const options = url.parse(req.url);
  console.log(options);
  options.headers = req.headers;
  const proxyRequest = http.request(options, function(proxyResponse) { // 创建请求来复制原始的请求
    proxyResponse.on('data', function(chunk) { // 监听数据，返回给浏览器
      console.log('proxyResponse length:', chunk.length);
      res.write(chunk, 'binary');
    });

    proxyResponse.on('end', function() { // 追踪代理请求完成
      console.log('proxied request ended');
      res.end();
    });

    res.writeHead(proxyResponse.statusCode, proxyResponse.headers); // 发送头部信息给服务器
  });

  req.on('data', function(chunk) { // 捕获从浏览器发送到服务器的数据
    console.log('in request length:', chunk.length);
    proxyRequest.write(chunk, 'binary');
  });

  req.on('end', function() { // 追踪原始的请求什么时候结束
    console.log('original request ended');
    proxyRequest.end();
  });
}).listen(8888); // 监听来自本地浏览器的连接

const https = require('https');
const promisify = require('util').promisify;

https.get[promisify.custom] = function getAsync(options) {
  return new Promise((resolve, reject) => {
    https.get(options, (response) => {
      response.end = new Promise((resolve) => response.on('end', resolve));
      resolve(response);
    }).on('error', reject);
  });
};
const rp = promisify(https.get);

(async () => {
  const res = await rp('https://jsonmock.hackerrank.com/api/movies/search/?Title=Spiderman&page=1');
  let body = '';
  res.on('data', (chunk) => body += chunk);
  await res.end;

  console.log(body);
})();

const dns = require('dns');

dns.resolve('www.chenng.cn', function (err, addresses) {
  if (err) {
    console.error(err);
  }

  console.log('Addresses:', addresses);
});

const crypto = require('crypto')

function aesEncrypt(data, key = 'key') {
  const cipher = crypto.createCipher('aes192', key)
  let crypted = cipher.update(data, 'utf8', 'hex')
  crypted += cipher.final('hex')
  return crypted
}

function aesDecrypt(encrypted, key = 'key') {
  const decipher = crypto.createDecipher('aes192', key)
  let decrypted = decipher.update(encrypted, 'hex', 'utf8')
  decrypted += decipher.final('utf8')
  return decrypted
}

const cp = require('child_process');

cp.execFile('echo', ['hello', 'world'], (err, stdout, stderr) => {
  if (err) { console.error(err); }
  console.log('stdout: ', stdout);
  console.log('stderr: ', stderr);
});

const cp = require('child_process');

const child = cp.spawn('echo', ['hello', 'world']);
child.on('error', console.error);
child.stdout.pipe(process.stdout);
child.stderr.pipe(process.stderr);

const cp = require('child_process');
const path = require('path');

const cat = cp.spawn('cat', [path.resolve(__dirname, 'messy.txt')]);
const sort = cp.spawn('sort');
const uniq = cp.spawn('uniq');

cat.stdout.pipe(sort.stdin);
sort.stdout.pipe(uniq.stdin);
uniq.stdout.pipe(process.stdout);

const cp = require('child_process');

cp.exec(`cat ${__dirname}/messy.txt | sort | uniq`, (err, stdout, stderr) => {
  console.log(stdout);
});

// parent.js
const cp = require('child_process');

const child = cp.fork('./child', { silent: true });
child.send('monkeys');
child.on('message', function (message) {
  console.log('got message from child', message, typeof message);
})
child.stdout.pipe(process.stdout);

setTimeout(function () {
  child.disconnect();
}, 3000);

// child.js
process.on('message', function (message) {
  console.log('got one', message);
  process.send('no pizza');
  process.send(1);
  process.send({ my: 'object' });
  process.send(false);
  process.send(null);
});

console.log(process);

const spawn = require('child_process').spawn;
const children = [];

process.on('exit', function () {
  console.log('killing', children.length, 'child processes');
  children.forEach(function (child) {
    child.kill();
  });
});

children.push(spawn('/bin/sleep', ['10']));
children.push(spawn('/bin/sleep', ['10']));
children.push(spawn('/bin/sleep', ['10']));

setTimeout(function () { process.exit(0); }, 3000);

process.env.UV_THREADPOOL_SIZE = 64

const cluster = require('cluster');
const http = require('http');
const numCPUs = require('os').cpus().length;

if (cluster.isMaster) {
  console.log(`主进程 ${process.pid} 正在运行`);
  for (let i = 0; i < numCPUs; i++) {
    cluster.fork();
  }

  cluster.on('exit', (worker, code, signal) => {
    console.log(`工作进程 ${worker.process.pid} 已退出`);
  });
} else {
  // 工作进程可以共享任何 TCP 连接。
  // 在本例子中，共享的是 HTTP 服务器。
  http.createServer((req, res) => {
    res.writeHead(200);
    res.end('Hello World');
  }).listen(8000);
  console.log(`工作进程 ${process.pid} 已启动`);
}

  isMainThread,
  parentPort,
  workerData,
  threadId,
  MessageChannel,
  MessagePort,
  Worker
} = require('worker_threads');

function mainThread() {
  for (let i = 0; i < 5; i++) {
    const worker = new Worker(__filename, { workerData: i });
    worker.on('exit', code => { console.log(`main: worker stopped with exit code ${code}`); });
    worker.on('message', msg => {
      console.log(`main: receive ${msg}`);
      worker.postMessage(msg + 1);
    });
  }
}

function workerThread() {
  console.log(`worker: workerDate ${workerData}`);
  parentPort.on('message', msg => {
    console.log(`worker: receive ${msg}`);
  }),
  parentPort.postMessage(workerData);
}

if (isMainThread) {
  mainThread();
} else {
  workerThread();
}

const assert = require('assert');
const {
  Worker,
  MessageChannel,
  MessagePort,
  isMainThread,
  parentPort
} = require('worker_threads');
if (isMainThread) {
  const worker = new Worker(__filename);
  const subChannel = new MessageChannel();
  worker.postMessage({ hereIsYourPort: subChannel.port1 }, [subChannel.port1]);
  subChannel.port2.on('message', (value) => {
    console.log('received:', value);
  });
} else {
  parentPort.once('message', (value) => {
    assert(value.hereIsYourPort instanceof MessagePort);
    value.hereIsYourPort.postMessage('the worker is sending this');
    value.hereIsYourPort.close();
  });
}

process.on('uncaughtException', (error) => {
  // 我刚收到一个从未被处理的错误
  // 现在处理它，并决定是否需要重启应用
  errorManagement.handler.handleError(error);
  if (!errorManagement.handler.isTrustedError(error)) {
    process.exit(1);
  }
});

process.on('unhandledRejection', (reason, p) => {
  // 我刚刚捕获了一个未处理的promise rejection,
  // 因为我们已经有了对于未处理错误的后备的处理机制（见下面）
  // 直接抛出，让它来处理
  throw reason;
});

const domain = require('domain');
const audioDomain = domain.create();

audioDomain.on('error', function(err) {
  console.log('audioDomain error:', err);
});

audioDomain.run(function() {
  const musicPlayer = new MusicPlayer();
  musicPlayer.play();
});

const memberSchema = Joi.object().keys({
 password: Joi.string().regex(/^[a-zA-Z0-9]{3,30}$/),
 birthyear: Joi.number().integer().min(1900).max(2013),
 email: Joi.string().email(),
});
 
function addNewMember(newMember) {
 //assertions come first
 Joi.assert(newMember, memberSchema); //throws if validation fails
 
 //other logic here
}

var winston = require('winston');
var moment = require('moment');

const logger = new (winston.Logger)({
  transports: [
    new (winston.transports.Console)({
      timestamp: function() {
        return moment().format('YYYY-MM-DD HH:mm:ss')
      },
      formatter: function(params) {
        let time = params.timestamp() // 时间
        let message = params.message // 手动信息
        let meta = params.meta && Object.keys(params.meta).length ? '\n\t'+ JSON.stringify(params.meta) : ''
        return `${time} ${message}`
      },
    }),
    new (winston.transports.File)({
      filename: `${__dirname}/../winston/winston.log`,
      json: false,
      timestamp: function() {
        return moment().format('YYYY-MM-DD HH:mm:ss')
      },
      formatter: function(params) {
        let time = params.timestamp() // 时间
        let message = params.message // 手动信息
        let meta = params.meta && Object.keys(params.meta).length ? '\n\t'+ JSON.stringify(params.meta) : ''
        return `${time} ${message}`
      }
    })
  ]
})

module.exports = logger

// logger.error('error')
// logger.warm('warm')
// logger.info('info')

# 配置 gzip 压缩
gzip on;
gzip_comp_level 6;
gzip_vary on;

# 配置 upstream
upstream myApplication {
  server 127.0.0.1:3000;
  server 127.0.0.1:3001;
  keepalive 64;
}

#定义 web server
server {
  # configure server with ssl and error pages
  listen 80;
  listen 443 ssl;
  ssl_certificate /some/location/sillyfacesociety.com.bundle.crt;
  error_page 502 /errors/502.html;

  # handling static content
  location ~ ^/(images/|img/|javascript/|js/|css/|stylesheets/|flash/|media/|static/|robots.txt|humans.txt|favicon.ico) {
  root /usr/local/silly_face_society/node/public;
  access_log off;
  expires max;
}

  {
  "extends": [
    "plugin:you-dont-need-lodash-underscore/compatible"
  ]
}

 const _ = require('lodash'),
  __ = require('underscore'),
  Suite = require('benchmark').Suite,
  opts = require('./utils');
  //cf. https://github.com/Berkmann18/NativeVsUtils/blob/master/utils.js

const concatSuite = new Suite('concat', opts);
const array = [0, 1, 2];

concatSuite.add('lodash', () => _.concat(array, 3, 4, 5))
  .add('underscore', () => __.concat(array, 3, 4, 5))
  .add('native', () => array.concat(3, 4, 5))
  .run({ 'async': true });

node --prof profile-test.js

npm install tick -g
node-tick-processor

yarn add heapdump -D

const heapdump = require('heapdump');
const string = '1 string to rule them all';

const leakyArr = [];
let count = 2;
setInterval(function () {
  leakyArr.push(string.replace(/1/g, count++));
}, 0);

setInterval(function () {
  if (heapdump.writeSnapshot()) console.log('wrote snapshot');
}, 20000);

// 使用10个哈希回合异步生成安全密码
bcrypt.hash('myPassword', 10, function(err, hash) {
  // 在用户记录中存储安全哈希
});

// 将提供的密码输入与已保存的哈希进行比较
bcrypt.compare('somePassword', hash, function(err, match) {
  if(match) {
   // 密码匹配
  } else {
   // 密码不匹配
  } 
});

const jwt = require('express-jwt');
const blacklist = require('express-jwt-blacklist');
 
app.use(jwt({
  secret: 'my-secret',
  isRevoked: blacklist.isRevoked
}));
 
app.get('/logout', function (req, res) {
  blacklist.revoke(req.user)
  res.sendStatus(200);
});

  const ExpressBrute = require('express-brute');
const RedisStore = require('express-brute-redis');

const redisStore = new RedisStore({
  host: '127.0.0.1',
  port: 6379
});

// Start slowing requests after 5 failed 
// attempts to login for the same user
const loginBruteforce = new ExpressBrute(redisStore, {
  freeRetries: 5,
  minWait: 5 * 60 * 1000, // 5 minutes
  maxWait: 60 * 60 * 1000, // 1 hour
  failCallback: failCallback,
  handleStoreError: handleStoreErrorCallback
});

app.post('/login',
  loginBruteforce.getMiddleware({
    key: function (req, res, next) {
      // prevent too many attempts for the same username
      next(req.body.username);
    }
  }), // error 403 if we hit this route too often
  function (req, res, next) {
    if (User.isValidLogin(req.body.username, req.body.password)) {
      // reset the failure counter for valid login
      req.brute.reset(function () {
        res.redirect('/'); // logged in
      });
    } else {
      // handle invalid user
    }
  }
);

FROM node:latest
COPY package.json .
RUN npm install
COPY . .
EXPOSE 3000
USER node
CMD ["node", "server.js"]

const express = require('express');
const app = express();
// body-parser defaults to a body size limit of 300kb
app.use(express.json({ limit: '300kb' })); 

// Request with json body
app.post('/json', (req, res) => {

    // Check if request payload content-type matches json
    // because body-parser does not check for content types
    if (!req.is('json')) {
        return res.sendStatus(415); // Unsupported media type if request doesn't have JSON body
    }

    res.send('Hooray, it worked!');
});

app.listen(3000, () => console.log('Example app listening on port 3000!'));

http {
    ...
    # Limit the body size for ALL incoming requests to 1 MB
    client_max_body_size 1m;
}

server {
    ...
    # Limit the body size for incoming requests to this specific server block to 1 MB
    client_max_body_size 1m;
}

location /upload {
    ...
    # Limit the body size for incoming requests to this route to 1 MB
    client_max_body_size 1m;
}

const saferegex = require('safe-regex');
const emailRegex = /^([a-zA-Z0-9])(([\-.]|[_]+)?([a-zA-Z0-9]+))*(@){1}[a-z0-9]+[.]{1}(([a-z]{2,3})|([a-z]{2,3}[.]{1}[a-z]{2,3}))$/;

// should output false because the emailRegex is vulnerable to redos attacks
console.log(saferegex(emailRegex));

// instead of the regex pattern, use validator:
const validator = require('validator');
console.log(validator.isEmail('liran.tal@gmail.com'));

const Sandbox = require("sandbox");
const s = new Sandbox();

s.run( "lol)hai", function( output ) {
  console.log(output);
  //output='Synatx error'
});

// Example 4 - Restricted code
s.run( "process.platform", function( output ) {
  console.log(output);
  //output=Null
})

// Example 5 - Infinite loop
s.run( "while (true) {}", function( output ) {
  console.log(output);
  //output='Timeout'
})

  // production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
        message: err.message,
        error: {}
    });
});

// using the express session middleware
app.use(session({  
 secret: 'youruniquesecret', // secret string used in the signing of the session ID that is stored in the cookie
 name: 'youruniquename', // set a unique name to remove the default connect.sid
 cookie: {
   httpOnly: true, // minimize risk of XSS attacks by restricting the client from reading the cookie
   secure: true, // only send cookie over https
   maxAge: 60000*60*24 // set cookie expiry length in ms
 }
}));

var cookieParser = require('cookie-parser');  
var csrf = require('csurf');  
var bodyParser = require('body-parser');  
var express = require('express');

// 设置路由中间件
var csrfProtection = csrf({ cookie: true });  
var parseForm = bodyParser.urlencoded({ extended: false });

var app = express();

// 我们需要这个，因为在 csrfProtection 中 “cookie” 是正确的
app.use(cookieParser());

app.get('/form', csrfProtection, function(req, res) {  
  // 将 CSRFToken 传递给视图
  res.render('send', { csrfToken: req.csrfToken() });
});

app.post('/process', parseForm, csrfProtection, function(req, res) {  
  res.send('data is being processed');
});

  <form action="/process" method="POST">  
  <input type="hidden" name="_csrf" value="{{csrfToken}}">

  Favorite color: <input type="text" name="favoriteColor">
  <button type="submit">Submit</button>
</form>  

  const fs = require('fs');
const exec = require('child_process').exec;

function watch() {
  const child = exec('node server.js');
  const watcher = fs.watch(__dirname + '/server.js', function () {
    console.log('File changed, reloading.');
    child.kill();
    watcher.close();
    watch();
  });
}

watch();

let app;
const express = require('express');
const routes = require('./routes');

module.exports = app = express();

app.use(express.json()); // 使用 JSON body 解析
app.use(express.methodOverride()); // 允许一个查询参数来制定额外的 HTTP 方法

// 资源使用的路由
app.get('/pages', routes.pages.index);
app.get('/pages/:id', routes.pages.show);
app.post('/pages', routes.pages.create);
app.patch('/pages/:id', routes.pages.patch);
app.put('/pages/:id', routes.pages.update);
app.del('/pages/:id', routes.pages.remove);

const express = require('express');
const app = express();
const Schema = require('validate');
const xml2json = require('xml2json');
const util = require('util');
const Page = new Schema();

Page.path('title').type('string').required(); // 数据校验确保页面有标题

function ValidatorError(errors) { // 从错误对象继承，校验出现的错误在错误中间件处理
  this.statusCode = 400;
  this.message = errors.join(', ');
}
util.inherits(ValidatorError, Error);

function xmlMiddleware(req, res, next) { // 处理 xml 的中间件
  if (!req.is('xml')) return next();

  let body = '';
  req.on('data', function (str) { // 从客户端读到数据时触发
    body += str;
  });

  req.on('end', function () {
    req.body = xml2json.toJson(body.toString(), {
      object: true,
      sanitize: false,
    });
    next();
  });
}

function checkValidXml(req, res, next) { // 数据校验中间件
  const page = Page.validate(req.body.page);
  if (page.errors.length) {
    next(new ValidatorError(page.errors)); // 传递错误给 next 阻止路由继续运行
  } else {
    next();
  }
}

function errorHandler(err, req, res, next) { // 错误处理中间件
  console.error('errorHandler', err);
  res.send(err.statusCode || 500, err.message);
}

app.use(xmlMiddleware); // 应用 XML 中间件到所有的请求中

app.post('/pages', checkValidXml, function (req, res) { // 特定的请求校验 xml
  console.log('Valid page:', req.body.page);
  res.send(req.body);
});

app.use(errorHandler); // 添加错误处理中间件

app.listen(3000);

// 监听用户注册成功消息，绑定邮件程序
const express = require('express');
const app = express();
const emails = require('./emails');
const routes = require('./routes');

app.use(express.json());

app.post('/users', routes.users.create); // 设置路由创建用户

app.on('user:created', emails.welcome); // 监听创建成功事件，绑定 email 代码

module.exports = app;

// 用户注册成功发起事件
const User = require('./../models/user');

module.exports.create = function (req, res, next) {
  const user = new User(req.body);
  user.save(function (err) {
    if (err) return next(err);
    res.app.emit('user:created', user); // 当用户成功注册时触发创建用户事件
    res.send('User created');
  });
};

const express = require('express');
const WebSocketServer = require('ws').Server;
const parseCookie = express.cookieParser('some secret'); // 加载解析 cookie 中间件，设置密码
const MemoryStore = express.session.MemoryStore; // 加载要使用的会话存储
const store = new MemoryStore();

const app = express();
const server = app.listen(process.env.PORT || 3000);

app.use(parseCookie);
app.use(express.session({ store: store, secret: 'some secret' })); // 告知 Express 使用会话存储和设置密码(使用 session 中间件)
app.use(express.static(__dirname + '/public'));

app.get('/random', function (req, res) { // 测试测试用的会话值
  req.session.random = Math.random().toString();
  res.send(200);
});

// 设置 WebSocket 服务器，将其传递给 Express 服务器
// 需要传递已有的 Express 服务（listen 的返回对象）
const webSocketServer = new WebSocketServer({ server: server });

// 在连接事件给客户端创建 WebSocket
webSocketServer.on('connection', function (ws) {
  let session;

  ws.on('message', function (data, flags) {
    const message = JSON.parse(data);

    // 客户端发送的 JSON，需要一些代码来解析 JSON 字符串确定是否可用
    if (message.type === 'getSession') {
      parseCookie(ws.upgradeReq, null, function (err) {
        // 从 HTTP 的更新请求中获取 WebSocket 的会话 ID
        // 一旦 WebSockets 服务器有一个连接，session ID 可以用=从初始化请求中的 cookies 中获取
        const sid = ws.upgradeReq.signedCookies['connect.sid'];

        // 从存储中获取用户的会话信息
        // 只需要在初始化的请求中传递一个引用给解析 cookie 的中间件
        // 然后 session 可以使用 session 存储的 get 方法加载
        store.get(sid, function (err, loadedSession) {
          if (err) console.error(err);
          session = loadedSession;
          ws.send('session.random: ' + session.random, {
            mask: false,
          }); // session 加载后会把一个包含了 session 值的消息发回给客户端
        });
      });
    } else {
      ws.send('Unknown command');
    }
  });
});

<!DOCTYPE html>
<html>
<head>
  <script>
    const host = window.document.location.host.replace(/:.*/, '');
    const ws = new WebSocket('ws://' + host + ':3000');

    setInterval(function () {
      ws.send('{ "type": "getSession" }'); // 定期向服务器发送消息
    }, 1000);

    ws.onmessage = function (event) {
      document.getElementById('message').innerHTML = event.data;
    };
  </script>
</head>

<body>
  <h1>WebSocket sessions</h1>
  <div id='message'></div><br>
</body>

</html>

{
  "alg": "HS256", // 签名的算法
  "typ": "JWT" // token 的类型
}

{
  // 7 个官方字段
  "iss": "签发人",
  "exp": "过期时间",
  "sub": "主题",
  "aud": "受众",
  "nbf": "生效时间",
  "iat": "签发时间",
  "jti": "编号",
  // 定义私有字段
  "name": "Chenng" 
}

  HMACSHA256(
  base64UrlEncode(header) + "." +
  base64UrlEncode(payload),
  secret) # secret 秘钥只有服务器知道

const Koa = require('koa');

const app = new Koa();

const mid1 = async (ctx, next) => {
  ctx.body = 'Hi';
  await next(); // next 执行下一个中间件
  ctx.body += ' there';
};
const mid2 = async (ctx, next) => {
  ctx.type = 'text/html; chartset=utf-8';
  await next();
};
const mid3 = async (ctx, next) => {
  ctx.body += ' chenng';
  await next();
};

app.use(mid1);
app.use(mid2);
app.use(mid3);

app.listen(2333);
// Hi chenng there

router
  .get('/api/dynamic_image/codewars', async (ctx, next) => {
    const res = await axios.get('https://www.codewars.com/users/ringcrl');
    const [, kyu, score] = res.data
      .match(/<div class="stat"><b>Rank:<\/b>(.+?)<\/div><div class="stat"><b>Honor:<\/b>(.+?)<\/div>/);
    const svg = `
      <svg xmlns="http://www.w3.org/2000/svg" width="80" height="20">
        <rect x="0" y="0" width="80" height="20" fill="#fff" stroke-width="2" stroke="#cccccc"></rect>
        <rect x="0" y="0" width="50" height="20" fill="#5b5b5b"></rect>
        <text x="5" y="15" class="small" fill="#fff" style="font-size: 14px;">${kyu}</text>
        <rect x="50" y="0" width="30" height="20" fill="#3275b0"></rect>
        <text x="53" y="15" class="small" fill="#fff" style="font-size: 14px">${score}</text>
      </svg>
    `;
    ctx.set('Content-Type', 'image/svg+xml');
    ctx.body = Buffer.from(svg);
    await next();
  });

利用 openssl 生成公钥私钥 
生成公钥：openssl genrsa -out rsa_private_key.pem 1024 
生成私钥：openssl rsa -in rsa_private_key.pem -pubout -out rsa_public_key.pem

  const crypto = require('crypto');
const fs = require('fs');

const publicKey = fs.readFileSync(`${__dirname}/rsa_public_key.pem`).toString('ascii');
const privateKey = fs.readFileSync(`${__dirname}/rsa_private_key.pem`).toString('ascii');
console.log(publicKey);
console.log(privateKey);
const data = 'Chenng';
console.log('content: ', data);

//公钥加密
const encodeData = crypto.publicEncrypt(
  publicKey,
  Buffer.from(data),
).toString('base64');
console.log('encode: ', encodeData);

//私钥解密
const decodeData = crypto.privateDecrypt(
  privateKey,
  Buffer.from(encodeData, 'base64'),
);
console.log('decode: ', decodeData.toString());

const redis = require('redis');
const redisClient = redis.createClient();
const getAsync = promisify(redisClient.get).bind(redisClient);

let codewarsRes = JSON.parse(await getAsync('codewarsRes'));
if (!codewarsRes) {
  const res = await axios.get('https://www.codewars.com/users/ringcrl');
  codewarsRes = res.data;
  redisClient.set('codewarsRes', JSON.stringify(codewarsRes), 'EX', 86000);
}

const schedule = require('node-schedule');
const axios = require('axios');

schedule.scheduleJob('* 23 59 * *', function () {
  axios.get('https://static.chenng.cn/api/dynamic_image/leetcode_problems');
  axios.get('https://static.chenng.cn/api/dynamic_image/leetcode');
  axios.get('https://static.chenng.cn/api/dynamic_image/codewars');
});