[fs - express.js] What's the problem?

Question

JavaScript

There are always problems reading FS files.
Here is the code:

fs.readFile('/../../../../../root/projects/kulonful.ru/hiden/index.html',  function(data) {
            console.log(data);
            res.setHeader('Content-Type', 'text/html; charset=utf-8');
            res.setHeader('Dev-Help', 'https://vk.com/kulonful');
            res.end(data);
}

Gives null in the log. The result is a blank page

Answer 1

Well, that's right, null means that there was no error while reading. Is it bad? If we assign one more argument to the callback function, then it will contain the successfully read file.

Answer 2

The first argument in the callback is an error, the read file is the second