event-loop

delay-el.js

/**
 * Shows how the event loop can be delayed to the execution of a timer.
 * inspired on node-js docs example: https://nodejs.org/en/docs/guides/event-loop-timers-and-nexttick/
 */

'use-strict';

const { spawn } = require('child_process');

// Create a task that takes 95ms to complete
new Promise((resolve) => {
    console.time('sleep');
    spawn('sleep', ['0.085']).on('close', () => {
        console.log('closed');
        console.timeEnd('sleep');
        
        resolve();
    });
}).then(() => {
    console.log('then');
    // block the thread for 10s
    const startCallback = Date.now();

    while (Date.now() - startCallback < 10) {
        1 + 1 // nothing, really...
    }
});

let timeoutScheduled = Date.now();

setTimeout(() => {
    const delay = Date.now() - timeoutScheduled;

    console.log(`${delay} ms have passed since I was scheduled`);
}, 100);

'done'