readFile.js

const fs = require('fs');
const Benchmark = require('benchmark');
const readline = require('readline');
const filePath = './testFile.txt';
const expectedFileSize = 1000010000;
let suite = new Benchmark.Suite();

/**
 * Generating a test file
 */
function generateFile() {
    for (let i = 0; i < 10000; i++) {
        let string = 'Test Data '.repeat(10000);

        fs.appendFileSync(filePath, string + '\n');
    }
}

// If the file doesn't exists generate data and write to file
if (!fs.existsSync(filePath)) {
    generateFile();
} else if (fs.statSync(filePath).size != expectedFileSize) {
    fs.unlinkSync(filePath);
    generateFile();
}

// Running the tests
suite
    .add('fs#readFileSync', function () {
        let string = fs.readFileSync(filePath);
    })
    .add(
        'fs#readFile',
        function (deferred) {
            let string = fs.readFile(filePath, (string) => deferred.resolve());
        },
        {
            // a flag to indicate the benchmark is deferred
            defer: true,
        }
    )
    .add(
        'readline',
        function (deferred) {
            let string = new Array();
            let lineReader = readline.createInterface({
                input: fs.createReadStream(filePath),
            });

            lineReader.on('line', (line) => {
                string.push(line);
            });

            lineReader.on('close', () => deferred.resolve());
        },
        {
            // a flag to indicate the benchmark is deferred
            defer: true,
        }
    )
    // Add listeners
    .on('cycle', function (event) {
        console.log(String(event.target));
    })
    .on('complete', function () {
        console.log(`Fastest is ${this.filter('fastest').map('name')}`);
    })
    // Run async
    .run({
        async: true,
    });