TypeError: Cannot read property 'readFileSync' of undefined NodeJS dom-parser

Question

Trying to use Dom-Parser with Discord.js. Couldn't find help from any where else. Error on line 15 fs.readFile I also had a lot problems getting fs working. First it wasn't defined then it could not be runned before initalization, just got that fixed (I hope)

// Discord stuff.
const Discord = require('discord.js');
const client = new Discord.Client();
const config = require('./config.json');
const token = config.token;

// DomParser
var DomParser = require('dom-parser');
var parser = new DomParser();
var data = fs.readFileSync(filepathHidden);

// Other requirements
var fs = require('fs');


// when getting online. 
client.once('ready', () => {
    console.log('WAHAHAHA IM ALIVE!');
}),

fs.readFile('https://url.com)', 'utf8', function(err, html){
    if (!err){
      var dom = parser.parseFromString(html);
  
      console.log(dom.getElementsByClassName('new_solution_box_title').innerHTML);
    }
  })

client.login(token);

Answer 1

var is hoisted.

So since you have var fs, there is a variable called fs in the function / module / global scope where you have that statement.

It starts out undefined.

When you say fs = require('fs') you assign the file system module to it. At that point it stops being undefined.

On the previous line when you try to read it with fs.readFileSync, you haven't yet defined it so you get an error.

Order matters.