JavaScript Promises, road to async/await - https://codingblast.com/javascript-promise-async-await

async.js

function someFunction(value, error) {
  return new Promise(function(resolve, reject) {
    if (value) {
      resolve(value);
    } else {
      reject(error);
    }
  });
}

async function mainFunction() {
  try {
    let value = await someFunction(null, 'Some error');
    console.log(value);
  } catch (error) {
    console.error(error);
  }
}

mainFunction();