Beginner LevelExpress JS
How do you access and inspect HTTP request headers in Express?
❓ Interview Prompt: Explain inspecting client HTTP request headers using lowercased req.headers map and case-insensitive req.get() / req.header().
Express provides two ways to read incoming HTTP request headers sent by clients:
1. 'req.headers' Object:
•
Lowercases all incoming header names automatically ('req.headers['authorization']', 'req.headers['user-agent']').
2. 'req.get(name)' / 'req.header(name)':
•
Case-insensitive helper method for extracting specific header values: 'req.get("Content-Type")' or 'req.get("authorization")'. Also supports special aliases like 'req.get("referer")'.
Code Implementation Example
javascript
import express from 'express';
const app = express();
app.get('/api/inspect-headers', (req, res) => {
// 1. Case-insensitive header retrieval via req.get()
const authHeader = req.get('Authorization');
const userAgent = req.get('user-agent');
// 2. Access lowercased headers object map
const contentType = req.headers['content-type'];
res.json({ authHeader, userAgent, contentType });
});💡Inspecting incoming HTTP request headers using req.get() and req.headers.
🎯 Interview Key Takeaway
Use req.get("Header-Name") for case-insensitive header retrieval, or access lowercased keys on req.headers.
#req.headers#req.get#Headers#Beginner
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