L3. File Handling in Node.js

console.log("File Handling");

1. File System Module (fs/promises)

• Asynchronous File System Operations using promises.

• Import necessary functions:

import { readFile, writeFile, appendFile, mkdir } from "fs/promises";

• Functions and their uses:

  • readFile → Reads data from an existing file.

  • writeFile → Creates a new file and writes data into it.

  • appendFile → Adds data to an existing file.

  • mkdir → Creates a new folder (directory).

---

2. Reading a File

const read_file = async (filename) => {
    const data = await readFile(filename, "utf-8");
    console.log(data);
};

Calling the Function:

read_file("sample.txt");

• Reads sample.txt and logs the content.

• "utf-8" ensures proper text encoding.

---

3. Creating a File & Writing Data

const create_file = async (filename, content) => {
    await writeFile(filename, content);
    console.log("File created");
};

Calling the Function:

create_file("AI.txt", "This is a testing file");

• Creates AI.txt and writes "This is a testing file" inside it.

---

4. Appending Data to a File

const append_file = async (filename, content) => {
    await appendFile(filename, content);
    console.log("Data appended");
};

Calling the Function:

append_file("AI.txt", " This is additional data");

• Adds "This is additional data" to AI.txt.

---

5. Creating a Folder (Directory)

const create_dir = async (dirname) => {
    await mkdir(dirname, { recursive: true });
    console.log("Folder created");
};

• recursive: true → Allows creating nested directories.

Calling the Function:

create_dir("components");   // Creates a folder named "components"
create_dir("AI/sub");       // Creates a subfolder inside "AI"

---