Working with Files

const fs = require("fs");
const path = require("path");

// Synchronous — blocks until done (fine for scripts, bad for servers)
const content = fs.readFileSync("data.txt", "utf8");
console.log(content);

// Asynchronous — non-blocking (preferred for servers)
fs.readFile("data.txt", "utf8", (error, content) => {
  if (error) {
    console.error("Error reading file:", error);
    return;
  }
  console.log(content);
});

// Promise-based (cleanest — use this)
const fsPromises = require("fs/promises");

async function readData() {
  const content = await fsPromises.readFile("data.txt", "utf8");
  const json    = JSON.parse(content);
  return json;
}

const { writeFile, mkdir, readdir, stat, unlink } = require("fs/promises");
const path = require("path");

// Write a file (creates it if it doesn't exist)
await writeFile("output.txt", "Hello, World!", "utf8");

// Write JSON
const data = { users: 100, courses: 12 };
await writeFile("data.json", JSON.stringify(data, null, 2));

// Create a directory
await mkdir("./logs", { recursive: true });  // recursive: no error if exists

// List directory contents
const files = await readdir("./src");
console.log(files);  // ["app.js", "utils.js", ...]

// Check if a file/directory exists
try {
  const info = await stat("./data.json");
  console.log("Is file:", info.isFile());
  console.log("Size:", info.size, "bytes");
} catch {
  console.log("File does not exist");
}

// Delete a file
await unlink("./temp.txt");