merge.csv

const fs = reqiure("fs");

(async () => {
	let files = [];
	let lineCount = 0;
	const directoryPath = ".";
	const fileType = "csv";

	try {
		const fileNames = fs.readdirSync(directoryPath);
		fileNames.forEach((fileName) => {
			const lastThree = fileName.substring(fileName.length - fileType.length);
			if (lastThree === fileType) {
				files.push(fileName);
			}
		});
	} catch (e) {
		console.error({ e });
	}
	console.log({ files });

	fs.writeFile("merged.csv", "", function(err) {
		if (err) throw err;
		console.log("File is created successfully.");
	});

	files.forEach((filePath) => {
		const csvString = fs.readFileSync(filePath, "utf8");
		fs.appendFile("merged.csv", csvString, (err) => {
			if (err) throw err;
			console.log("File is merged successfully.");
		});
	});
})();