how to define fs in node js code example

Example 1: fs writefile node

const fs = require('fs')

const content = 'Some content!'

fs.writeFile('/Users/joe/test.txt', content, err => {
  if (err) {
    console.error(err)
    return
  }
  //file written successfully
})

Example 2: javascript fs read

fs.readFile('/etc/passwd', (err, data) => {
  if (err) throw err;
  console.log(data);
});