HTTP & APIs
HTTP Status Codes
3-digit standard response numbers that instantly communicate if an HTTP request succeeded or failed.
Diagram
Status Code Families: ───────────────────────────────────────── 1xx Informational (connecting...) 2xx ✅ Success (request completed!) 3xx ↪ Redirect (resource moved) 4xx ⚠️ Client Error (invalid request body) 5xx 💥 Server Error (database crashed) ─────────────────────────────────────────
In Depth
HTTP Status Codes are standardized 3-digit integers returned in every server response. They serve as metadata indicating how the request was handled.
Code Example
Handling response codes in API controllers
app.post('/api/users', (req, res) => {
if (!req.body.email) {
return res.status(400).json({ error: 'Email is required' }); // 400 Bad Request
}
const isDuplicate = checkDuplicate(req.body.email);
if (isDuplicate) {
return res.status(409).json({ error: 'Email already registered' }); // 409 Conflict
}
const newUser = saveUser(req.body);
return res.status(201).json(newUser); // 201 Created
});