writing files in javascript

<script> 
// Requiring fs module in which 
// writeFile function is defined. 
const fs = require('fs') 
  
// Data which will write in a file. 
let data = "Learning how to write in a file."
  
// Write data in 'Output.txt' . 
fs.writeFile('Output.txt', data, (err) => { 
      
    // In case of a error throw err. 
    if (err) throw err; 
}) 
</script> 

<script> 
// Requiring fs module in which 
// writeFile function is defined. 
const fs = require('fs') 
  
// Data which will write in a file. 
let data = "Learning how to write in a file."
  
// Write data in 'Output.txt' . 
fs.writeFile('Output.txt', data, (err) => { 
      
    // In case of a error throw err. 
    if (err) throw err; 
}) 
</script> 

'use strict'

const fs = require('fs');

let fileContent = 'I can write';
fs.writeFileSync('message.txt', fileContent);