generator-while.js

#!/usr/bin/env node

'use strict';

import 'babel-polyfill';
import fs from 'fs';

const PREFIX = './sample/';

const read = (file) => {
  fs.readFile(PREFIX + file, 'utf-8', (err, data) => {
    if (err) {
      return console.error(err);
    }
    data = data.replace('\n', '');
    console.log(data);
    g.next(data);
  })
};

const gfn = function*(file) {
  try {
    let y = yield read(file);
    while (y !== 'goal.') {
      y = yield read(y);
    }
  } catch (err) {
    console.error(err);
  }
};

const g = gfn('a.txt');
g.next();

promise-recursive.js

#!/usr/bin/env node

'use strict';

import 'babel-polyfill';
import fs from 'fs';

const PREFIX = './sample/';

const promise = (file) => {
  return new Promise((resolve, reject) => {
    fs.readFile(PREFIX + file, 'utf-8', (err, data) => {
      if (err) {
        return reject(new Error(err));
      }
      resolve(data);
    });
  }).then((val) => {
    val = val.replace('\n', '');
    console.log(val);
    if (val === 'end') {
      return;
    }
    return promise(val);
  });
};

promise('a.txt');