Three ways

  1. callbacks
  2. sync
  3. promises

print all files in a given directory

under project dir:

bamba
	f1.txt
	f2.txt
	f3.txt

first import fs and path

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

generate the directory path

const bambaPath = path.join(__dirname, 'bamba');

run readdir function

fs.readdir(bambaPath, (err, files) => {
	if (err) {
		console.error(err);
		return;
	}

	console.log(files);
});

the callback way is asynchronous

the Sync way

console.log(fs.readdirSync(bambaPath));

currently an error will crash the process.

so we should add try{.js} and catch{.js} blocks.

try {
	console.log(fs.readdirSync(bambaPath));
}
catch (err) {
	console.error(err);
}

fs.promises.readdir(bambaPath)
	.then(files => console.log(files));

in case of an error this program will crash the process.

so we should add the catch method.

fs.promises.readdir(bambaPath)
	.then(files => console.log(files))
	.catch(err => console.error(err));

let’s also use async await syntax

const files = await fs.promises.readdir(bambaPath);
console.log(files);

this will cause an error

await reserved word can be used only in a function with the async key word.

nisim();

async function nisim() {
	const files =
		await fs.promises.readdir(bambaPath);
	console.log(files);
}

what if an error will happen?

just use try{.js} and catch{.js} blocks.

nisim();

async function nisim() {
	try {
		const files =
			await fs.promises.readdir(bambaPath);
		console.log(files);
	}
	catch (err) {
		console.error(err);
	}
}

other useful fs functions

  • mkdir
  • rmdir
  • readFile
  • writeFile
  • appendFile
  • rm
  • cp
  • rename

writeFile and appendFile create the file if it doesn’t exist.

readFile requires a second argument for encoding.

we mostly (if not only) use utf8

// inside async function
const content = await fs.readFile(bambaPath, 'utf8');
console.log(content);