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

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

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