Node blocking and non blocking IO

Blocking IO

const fs = require('fs');
console.log('hi 1')
const data = fs.readFileSync('./file.md', 'utf8'); // blocks here until file is read
console.log(data);
console.log('hi 3')

file.txt

2

Non Blocking IO

// Non-blocking
console.log('hi 1')

const fs = require('fs');
fs.readFile('./file.md','utf8', (err, data) => {
  if (err) throw err;
  console.log(data);
});

console.log('hi 3')