res.status for status codes in Express

Introduction

res.status sets the HTTP status code for the response. It tells the browser or client if the request was successful or if there was an error.

When you want to tell the client that a request was successful (like 200 OK).

When you want to indicate a resource was created (like 201 Created).

When you want to show an error happened (like 404 Not Found).

When you want to redirect the client (like 302 Found).

When you want to signal the client to try again later (like 503 Service Unavailable).

Syntax

Express

res.status(statusCode)

statusCode is a number like 200, 404, or 500.

You usually chain res.status() with res.send() or res.json() to send the response.

Examples

Sends a 200 OK status with a simple text message.

Express

res.status(200).send('OK')

Sends a 404 Not Found status with a message.

Express

res.status(404).send('Page not found')

Sends a 201 Created status with a JSON object.

Express

res.status(201).json({ id: 123 })

Sample Program

This Express app has three routes. Each route sends a different HTTP status code using res.status() and a message or JSON response.

Express

import express from 'express';
const app = express();

app.get('/success', (req, res) => {
  res.status(200).send('Request was successful');
});

app.get('/notfound', (req, res) => {
  res.status(404).send('Resource not found');
});

app.get('/created', (req, res) => {
  res.status(201).json({ message: 'New item created' });
});

app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

Important Notes

Always set the status code before sending the response.

If you don't set a status code, Express defaults to 200.

Use correct status codes to help clients understand the result of their request.

Summary

res.status sets the HTTP status code for the response.

It helps communicate success, errors, or other states to the client.

Always chain it with res.send() or res.json() to send the response.