process.nextTIck

timers.js

'use strict';

// https://nodejs.org/api/process.html#process_process_nexttick_callback_args
//
// Says:
// 
// "It runs before any additional I/O events (including timers) fire
// in subsequent ticks of the event loop."
//
// Question is, does "additional" mean events whose listeners are added
// _additionally_, i.e., after the =nextTick= call, or additional as in anything
// that isn't the cb passed to =nextTick=? (Answer: the latter. It will block any async
// events, no matter when they are registered.)
//
// Uncomment function calls below for demo:

const fs = require('fs');
const stream = fs.createReadStream('/dev/random', {
  encoding: 'base64', flags: 'r'
});

setTimeout(process.exit, 3e3); // =starve= will even starve this, though.

stream.on('data', chunk => console.log(`${chunk.length} bytes from the wire`));

function starve () {
  console.log('So hungry...');
  process.nextTick(starve);
}

function interleave () {
  console.log('Excuse me, sir...?');
  setTimeout(interleave, 0);
}

// Uncomment this to block I/O:
// starve();

// Uncomment this to not block:
// interleave();