Category: JavaScript Answers

Sometimes, we want to determine a user’s IP address in Node.js.

In this article, we’ll look at how to determine a user’s IP address in Node.js.

How to determine a user’s IP address in Node.js?

To determine a user’s IP address in Node.js, we can use the req.socket.remoteAddress property.

For instance, we write

app.post('/get/ip/address', (req, res) => {
  res.send(req.socket.remoteAddress)
})

to return the user’s IP address that we get from req.socket.remoteAddress as the response.

Conclusion

To determine a user’s IP address in Node.js, we can use the req.socket.remoteAddress property.

Sometimes, we want to specify the required Node.js version in package.json.

In this article, we’ll look at how to specify the required Node.js version in package.json.

How to specify the required Node.js version in package.json?

To specify the required Node.js version in package.json, we can set the engines.npm and engines.node property in package.json.

For instance, we write

"engines": {
  "npm": ">=7.0.0",
  "node": ">=16.0.0"
}

to set the required Node version to 16.0.0 or higher.

Conclusion

To specify the required Node.js version in package.json, we can set the engines.npm and engines.node property in package.json.

Sometimes, we want to check if path is file or directory with Node.js.

In this article, we’ll look at how to check if path is file or directory with Node.js.

How to check if path is file or directory with Node.js?

To check if path is file or directory with Node.js, we can use the fs.lstat with the isDirectory method.

For instance, we write

(await fs.lstat(pathString)).isDirectory() 

to call fs.lstat with the pathString to return a promise which resolves to the stat object.

Then we call isDirectory on the stat object to check if the pathString points to a directory.

To check if the pathString points to a file, we can use the isFile method.

For instance, we write

(await fs.lstat(pathString)).isFile() 

Conclusion

To check if path is file or directory with Node.js, we can use the fs.lstat with the isDirectory method.

Sometimes, we want to return JSON using Node.js and Express.

In this article, we’ll look at how to return JSON using Node.js and Express.

How to return JSON using Node.js and Express?

To return JSON using Node.js and Express, we can use the res.end and res.json method.

For instance, if we use the http package, we write

const http = require('http');

const app = http.createServer((req, res) => {
  res.setHeader('Content-Type', 'application/json');
  res.end(JSON.stringify({
    a: 1
  }, null, 3));
});
app.listen(3000);

to call http.createServer to create the server.

Then we call res.end with the stringified JSON object as the response.

With Express, we call app.json with

res.json({ a: 1 });

to return the JSON response with the object.

Conclusion

To return JSON using Node.js and Express, we can use the res.end and res.json method.

Sometimes, we want to enable HTTPS on Express.js and Node.js.

In this article, we’ll look at how to enable HTTPS on Express.js and Node.js.

How to enable HTTPS on Express.js and Node.js?

To enable HTTPS on Express.js and Node.js, we can read the certificate files and use them when we create the server.

For instance, we write

const fs = require('fs');
const http = require('http');
const https = require('https');
const privateKey = fs.readFileSync('sslcert/server.key', 'utf8');
const certificate = fs.readFileSync('sslcert/server.crt', 'utf8');

const credentials = {
  key: privateKey,
  cert: certificate
};
const express = require('express');
const app = express();

const httpServer = http.createServer(app);
const httpsServer = https.createServer(credentials, app);

httpServer.listen(8080);
httpsServer.listen(8443);

to read the private key and certificate file with readFileSync.

Then we call createServer with the credentials object to let us run our web server with our certificate and key files via HTTPS.

And then we listen to the for HTTP and HTTPS requests with listen with different ports.

Conclusion

To enable HTTPS on Express.js and Node.js, we can read the certificate files and use them when we create the server.