eventLoop.js

/**
 * Event loop Logic:
 *
 * When the call stack gets empty:
 * 
 * While the queue is not empty:
 * event = dequeue an event
 * if there is a callback:
 *  call the event's callback 
 */

const fs = require('fs');

//2.
let bar;

const printNextTick = () => console.log('bar', bar);

const someAsyncApiCall = (cb) => process.nextTick(cb);

//1.
const immediately = () => console.log('This is immediately');

const printHello = () => console.log('Hello');

const blockFor500ms = () => {};

const useImportedTweets = (error, data) => {
    const tweets = JSON.parse(data)
    console.log(tweets.tweet);
};

//execute context
setTimeout(printHello, 0);

fs.readFile('./tweets.json', useImportedTweets);

blockFor500ms();

console.log('Me first');

setImmediate(immediately);

//2.
someAsyncApiCall(printNextTick);

bar = 1;