How can I access DOM Elements using Node JS?

JAVASCRIPT FILE

const path = require('path');
const http = require('http');
const fs = require('fs');

const dir = '../frontend/';

const server = http.createServer((request, respond) => {
      console.log(request.url);

      respond.writeHead(200, {
            'Content-Type': 'text/html',
      });

      const readStream = fs.createReadStream(dir + 'index.html', 'utf-8');
      readStream.pipe(respond);
});

const icons = 'icons/';

fs.readdir(icons, (error, files) => {
      if (error) throw error;

      files.forEach((file) => {
            if (path.extname(file) == '.svg') {
                  // I want to append this filename in the DOM Element.
                  document.querySelector('.container').innerHTML = file; // Like This
                  // console.log(file); 
            }
      });
});

server.listen(3000, 'localhost');

HTML File

<div class="container"></div>

Whenever I'm trying to execute above code it gives me an error like this

                  document.querySelector('.container').innerHTML = file;
                  ^

ReferenceError: document is not defined
    at D:\Framework Final\backend\server.js:26:19
    at Array.forEach (<anonymous>)
    at D:\Framework Final\backend\server.js:23:13
    at FSReqCallback.oncomplete (fs.js:171:23)

Can anyone tell me how can I achieve the same without getting an error.

Solution 1:

The error above is very explicit:

document is not defined

document is not exist in Node (e.g. server) environment, it's exist only in browser.

You will need to use separate library to parse your HTML file in order to do queries like querySelector('.container') and etc.

Libraries to take a look (as an example):

https://github.com/taoqf/node-fast-html-parser

https://github.com/cheeriojs/cheerio

Solution 2:

In NodeJS, the document Object doesn't exist. You can't access DOM-Nodes or anything in the DOM in NodeJS.

NodeJS is serverside Javascript.

If you want any data from the client, you have to add client-side code and send the data from the client to the server. This is done with a post-request. In the Backend, you have to setup a server with routes. To setup a server in NodeJS, use Express (frequently used). Google about it.