Pollify

Produces a stream of events by polling a provided function at a given rate. This rate is the minimum rate, not the exact rate (similar to setTimeout). The provided function is only polled when the previous execution has completed. This has the effect of making async calls execute in series.

Features

• Can poll promises, callback functions, and regular functions.
• Pollify is non-blocking. Will continuously poll a synchronous function in a non-blocking way.
• Handles whether to use setTimeout or setImmediate for you.

Installation

npm install pollify

Usage

Polls are automatically started for you when you create them.

Pollify a function

const Pollify = require('pollify');
 
function fn(arg1, arg2, cb) { ... }
let poll = Pollify({ rate: 1000, mode: 'callback' }, fn, arg1, arg2);

Pollify(options, pollFn, arg1, arg2, ...)

• options.rate the rate with which to poll pollFn
• options.mode the return type of pollFn
  • Can be callback, promise, or return for regular functions
• pollFn the function to be polled
• arg1, arg2, ... the arguments with which to call pollFn with

Listen for polled data

poll.on('data', (data, timestamp) => { ... });

Listen for errors from the polled function

poll.on('error', (e) => { ... });

Stop and start the poll

poll.stop();
poll.start();

But Why

Recently worked on a project where I needed to poll async functions in series. Made this for convenience and decided to share it.