Access File descriptor in nodejs

fs.js

const fs = require('fs')

fs.open('./index.js', 'r', (err, fd) => {
    //Access fd here
    
    if(err) return "error while open FD";
    
    fs.readFile(fd, function(err, msg) {
            if(err) return "error while read file";
        console.log('msg===', msg.toString())

    })
});