Node.js fs.filehandle.chmod() Method

// Node.js program to demonstrate the 
// fs.filehandle.chmod() method
const fs = require('fs');
const fsPromises = fs.promises;

console.log("content of file before "
        + "operation :- " +
        (fs.readFileSync('example.txt')));

// Initiating asynchronise function
async function funct() {

    // Initializing filehandle
    let filehandle = null;

    try {

        // Creating and initiating filehandle
        filehandle = await fsPromises
                .open('example.txt', 'r+');

        // Modifying the file permission
        // by using chmod() method
        const prom = filehandle.chmod(1);

    } finally {

        if (filehandle) {

            // Close the file if it is opened.
            console.log("permission is changed"
                        + " to read only");

            console.log("content of file before"
                    + " operation :- " +
                (fs.readFileSync('example.txt')));

            await filehandle.close();
        }
    }
}

funct().catch(console.error);

// Node.js program to demonstrate the 
// fs.filehandle.chmod() method
const fs = require('fs');
const fsPromises = fs.promises;

// data for the new file
let data = "This is a file containing"
        + " a collection of books.";

// Name of the file to be created
let file = "books.txt";

// Creating the new file 'books.txt'
fs.writeFile(file, data, (err) => {

    // Catching error
    if (err) {
        console.log(err);
    }
});

// Using fs.exists() method 
fs.exists(file, (exists) => {
    if (exists) {
        console.log("content of file "
            + "before operation :- " +
            (fs.readFileSync(file)));
    }
});

// Initiating asynchronise function
async function funct() {

    // Initializing filehandle
    let filehandle = null;

    try {

        // Creating and initiating  filehandle
        filehandle = await fsPromises.open(file, 'r+');

        // Modifying the file permission
        // by using chmod() method
        const prom = filehandle.chmod(1);

    } finally {

        if (filehandle) {

            // Close the file if it is opened.
            console.log("permission is "
                + "changed to read only");
                
            console.log("content of file"
                + "after operation :- " +
                (fs.readFileSync(file)));

            await filehandle.close();
        }
    }
}

funct().catch(console.error);