One way to retry promises

promise-retry-1.js

const lodash = require('lodash');

function main () {

  // Arbitrary async operation. Sums two coin-flips (random 0 or 1). Only resolves when the sum is 0.
  function asyncOperation() {
    return new Promise((resolve, reject) => {
      let sum = lodash(new Array(2))
      .fill(null)
      .map(() => Math.round(Math.random()))
      .reduce((accum, next) => accum + next, 0);

      console.log('Sum of the array is: ' + sum);

      if (sum === 0) {
        resolve();
      }
      else {
        reject('Not an error');
      }
    });
  }

  function retryOperation(resolve,reject) {
    return asyncOperation()
    .then(() => {
      console.log('Operation succeeded');
      resolve('Success');
    })
    .catch(reason => {
      console.log('Operation failed; retrying');
      if (reason === 'Not an error') {
        return retryOperation(resolve, reject);
      }
      else {
        reject(reason);
      }
    })
  }

  return new Promise((resolve, reject) => {
    return retryOperation(resolve, reject);
  })
  .then(() => {
    console.log('Success');
  })
  .catch(error => {
    console.log(error);
  });
}

main();