How to do repeated requests until one succeeds without blocking in node?

Question

I have a function that takes a parameter and a callback. It\'s supposed to do a request to a remote API and get some info based on the parameter. When it gets the info, it needs

Answer 1

I found Dmitry's answer using the async utility library very useful and the best answer.

This answer expands his example to a working version that defines the apiMethod function and passes it a parameter. I was going to add the code as a comment but a separate answer is clearer.

const async = require('async');

const apiMethod = function(uri, callback) {
  try {
    // Call your api here (or whatever thing you want to do) and assign to result.
    const result = ...
    callback(null, result);
  } catch (err) {
    callback(err);
  }
};

const uri = 'http://www.test.com/api';

async.retry(
    { times: 5, interval: 200 },
    function (callback) { return apiMethod(uri, callback) },
    function(err, result) {
      if (err) {
        throw err; // Error still thrown after retrying N times, so rethrow.
      }
  });

Retry documentation: https://caolan.github.io/async/docs.html#retry

Note, an alternative to calling apiMethod(uri, callback) in the task is to use async.apply:

async.retry(
        {times: 5, interval: 200},
        async.apply(task, dir),
        function(err, result) {
          if (err) {
            throw err; // Error still thrown after retrying N times, so rethrow.
          }
      });

I hope this provides a good copy/paste boiler plate solution for someone.