[Solved] What is wrong with this code snippet?res.setHeader('Content-Type', 'text/html'); res.end('Hello'); res.setHeader('X-Test', '123'); | Node.js

Node.js - HTTP Module

What is wrong with this code snippet?

res.setHeader('Content-Type', 'text/html');
res.end('Hello');
res.setHeader('X-Test', '123');

Ares.end() must be called with no arguments

BContent-Type header value is invalid

CHeaders cannot be set after res.end() is called

DX-Test header name is reserved and cannot be used

Step-by-Step Solution

Solution:

Step 1: Understand response lifecycle
Once res.end() is called, the response is finished and headers cannot be modified.
Step 2: Identify the error in code order
The code tries to set a header after ending the response, which is invalid and will cause an error.
Final Answer:
Headers cannot be set after res.end() is called -> Option C
Quick Check:
Set headers before res.end() only = A [OK]

Quick Trick: Set all headers before calling res.end() [OK]

Common Mistakes:

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What is wrong with this code snippet?