Blocking Promise

waitPromiseValue.js

'use strict'

const Promise = require('bluebird');
const fs = require('fs');
const deasync = require('deasync');

function readFile(f) {
  return new Promise(function (resolve, reject) {
   let file = fs.readFileSync(f);
   resolve(file);
  }).delay(5000)
}

function waitPromiseValue (p) {
  var value;

  let i = setInterval(() => {
    if (p.isFulfilled()) {
      value = p.value();
    }
  }, 400);

  while (!value) {
    deasync.runLoopOnce();
  }

  clearInterval(i);
  return value;
}

let p = readFile('index.js');
let v = waitPromiseValue(p);
console.log(v.toString());