I want to know how to compress and transfer files such as js in node.js.

The gzip is handled by Web Server Settings. If you're using Apache, read this article if you're using NGINX, read this article.

Just to give you the basics

https://nodejs.org/api/zlib.html

You can use zlib

Pipe to a file stream object that reads a file You can connect gzip and response objects sequentially.

And in order to get it right on your browser, Write 'Content-Encoding':'gzip' for the response header value.

const zlib = require('zlib');
const http = require('http');
const fs = require('fs');
http.createServer((request, response) => {
    const raw = fs.createReadStream('something.js');
    response.writeHead(200, { 'Content-Encoding': 'gzip' });
    raw.pipe(zlib.createGzip()).pipe(response);
}).listen(3000);

All this is possible with nodes alone, of course

At the actual service level, the additional settings for these static resources are: As @Yupto-gun said, it is more common to process it with a web server setting.