Reads a file line by line and returns a string array in JavaScript and Node.js.

readLines.js

'use strict';

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

function readLines(fileName) {
	return new Promise((resolve, reject) => {
		if (!fs.existsSync(fileName)) {
			return reject('File not found: ' + fileName);
		}

		let rl = readline.createInterface({
			input: fs.createReadStream(fileName),
			console: false
		});

		let lines = [];
		rl.on('line', line => lines.push(line));
		rl.on('close', () => resolve(lines));
		rl.on('error', err => reject(err));
	});
}

module.exports = readLines;