SOURCE

// node_modules\@types\node\fs.d.ts
// fs.readFile(fileName, callback);
// fs.writeFileSync(reportFilepath, reportHtml);
// fs.readFileSync( filePath, {
//       encoding: 'utf8'
//     } )
// fs.createReadStream("./index.html")
// fs.existsSync(dir)
// fs.mkdirSync(dir)
// write.sync( filePath, data )

const fs = require('fs');


// fs.createReadStream
// 首页路由
const router = new Router();
router.get("/", (ctx) => {
  ctx.response.type = "html";
  ctx.response.body = fs.createReadStream("./index.html");
});

// 目录不存在，如何创建它
const fs = require('fs'); 
const createDirIfNotExists = dir => (!fs.existsSync(dir) ? fs.mkdirSync(dir) : undefined); 
// Example 
createDirIfNotExists('test'); // creates the directory 'test', if it doesn't exist

// 获取某个文件中的某个参数
async function asyncAwaitTask() {
  const { version } = fs.readFileSync('package.json');
  console.log(version);
  await Promise.resolve('some result');
}

// 正常版本的readFile（多参数版本）
fs.readFile(fileName, callback);

// Thunk版本的readFile（单参数版本）
var Thunk = function (fileName) {
  return function (callback) {
    return fs.readFile(fileName, callback);
  };
};

var readFileThunk = Thunk(fileName);
readFileThunk(callback);


// 文件读写操作
var fs = require( 'fs' );
var write = require( 'write' );
var flatted = require( 'flatted' );

module.exports = {
  tryParse: function ( filePath, defaultValue ) {
    var result;
    try {
      result = this.readJSON( filePath );
    } catch (ex) {
      result = defaultValue;
    }
    return result;
  },

  /**
   * Read json file synchronously using flatted
   *
   * @method readJSON
   * @param  {String} filePath Json filepath
   * @returns {*} parse result
   */
  readJSON: function ( filePath ) {
    return flatted.parse( fs.readFileSync( filePath, {
      encoding: 'utf8'
    } ) );
  },

  /**
   * Write json file synchronously using circular-json
   *
   * @method writeJSON
   * @param  {String} filePath Json filepath
   * @param  {*} data Object to serialize
   */
  writeJSON: function ( filePath, data ) {
    write.sync( filePath, flatted.stringify( data ) );
  }
};