Node.js fsPromises.writeFile() Method

The fsPromises.writeFile() method asynchronously writes data to a file and replaces the file by default, with optional settings to control its behavior.

Writes data to a file asynchronously using Promises.
Replaces the file if it already exists.
Supports an options parameter to customize behavior.
Resolves the Promise with no value on successful completion.

Syntax

fsPromises.writeFile( file, data, options )

file: String, Buffer, URL, or file descriptor indicating the file path where data will be written
data: String, Buffer, TypedArray, or DataView to be written to the file
options: String or object to control write behavior (encoding, mode, and flag)
encoding: Specifies file encoding, default is utf8
mode: Specifies file permissions, default is 0o666
flag: Specifies the write flag, default is w
Returns: Promise that resolves on successful completion

Below examples illustrate the fsPromises.writeFile() method in Node.js:

[Example 1]: Create and write content into movies.txt asynchronously using fsPromises.writeFile() in Node.js

javascript

// Node.js program to demonstrate the 
// fsPromises.writeFile() method 

// Import the filesystem module 
const fs = require('fs');
const fsPromises = require('fs').promises;
let data = "This is a file containing"
        + " a collection of movies.";

(async function main() {
    try {
        await fsPromises.writeFile(
                "movies.txt", data)

        console.log("File written successfully");
        console.log("The written file has"
            + " the following contents:");

        console.log("" + 
            fs.readFileSync("./movies.txt"));

    } catch (err) {
        console.error(err);
    }
})();

Output:

File written successfully
The written file has the following contents:     
This is a file containing a collection of movies.

[Example 2]: Write data to a file asynchronously using fsPromises.writeFile() in Node.js

javascript

// Node.js program to demonstrate the 
// fsPromises.writeFile() method 

// Import the filesystem module 
const fs = require('fs');
const fsPromises = require('fs').promises;
let data = "This is a file containing"
        + " a collection of books.";

(async function main() {
    try {

        await fsPromises.writeFile(
                "books.txt", data, {
            encoding: "utf8",
            flag: "w",
            mode: 0o666
        });

        console.log("File written successfully\n");
        console.log("The written has the "
                + "following contents:");

        console.log("" + 
            fs.readFileSync("books.txt"));
    }
    catch (err) {
        console.error(err);
    }
})();

Output:

File written successfully

The written has the following contents:
This is a file containing a collection of books.

Reference: https://nodejs.org/api/fs.html#fs_fspromises_writefile_file_data_options

Node.js fsPromises.writeFile() Method

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