kchoo-keep-doing

A helper function for looping async tasks (probably obsolete with async/await inside loops, but that isn't supported by AWS lambda functions yet)

Usage

It's a little complicated, the idea is:

keepDoing() takes two arguments:

• the "main" function you want to execute every iteration
  • this has N + 2 parameters, where N is the number of arguments you want to pass for each iteration
  • the last two parameters are like resolve() and reject() of Promise, call the first to continue looping with new arguments, call the second to stop (with the value you want keepDoing()'s Promise to resolve with)
• the initial arguments you want to pass into your function

// function for counting from 0 to 10, in increments of 2, with 500 milliseconds between each number

const keepDoing = require('kchoo-keep-doing');

const numIterations = 10;
const step = 2;
const period = 500;

const loopPromise = keepDoing(
  function (i, next, stop) {
    if (i >= numIterations) {
      stop(i);
    } else {
      setTimeout(function () {
        next(i + step);
      }, period);
    }
  },
  0
);

loopPromise.then(function (finalI) { console.log(`Performed ${finalI} iterations`); });

Coming soon

Doing batches of async tasks. Say you want to do 50 tasks, and they're independent, but you only want to do 10 at a time. I want to add logic that does N tasks in parallel, waits for them all to call next(), and then kicks off the next N tasks.