Search string in file NodeJS - FULL file in memory

search-os.js

const osType = require('os').type();
const {spawn} = require('child_process');

const searchOs = (filename, text) => {
    return new Promise((resolve) => {

        if (osType === 'Windows_NT') {
            console.log('Searching using WINDOWS FIDSTR');

            let child = spawn('findstr', [
                    '/i',
                    '/s',
                    '/c:' + text, 'file/' + filename + '.txt'],
                {cwd: 'C:/workspace_private/nodejs-search-text/'});

            let results = []
            child.stdout.on('data', function (data) {
                if (data) {
                    results = results.concat(data.toString().split("\r\n"))
                    results.pop()
                }
            });
            child.stderr.on('data', function (data) {
                console.log('stderr: ' + data);
            });
            child.on('close', function (code) {
                console.log('child process exited with code ' + code);
                resolve(results)
            });

        }
    })

}

Related to article https://medium.com/codex/achieve-the-best-performance-search-a-string-in-file-using-nodejs-6a0f2a3b6cfa