Request size limits in Express - Mini Project: Build & Apply

Set Request Size Limits in Express

📖 Scenario: You are building a simple Express server that accepts JSON data from clients. To protect your server from very large requests that could slow it down or cause errors, you want to set a limit on the size of incoming JSON payloads.

🎯 Goal: Create an Express server that uses the built-in express.json() middleware with a request size limit of 100kb. This will ensure the server only accepts JSON requests up to 100 kilobytes in size.

📋 What You'll Learn

Create an Express app instance called app

Use express.json() middleware with the option limit: '100kb'

Add a POST route at /data that responds with status 200

Start the server listening on port 3000

💡 Why This Matters

🌍 Real World

Limiting request size is important to prevent clients from sending too much data, which can slow down or crash servers.

💼 Career

Backend developers often configure middleware like express.json() with size limits to build secure and reliable APIs.

1

Create Express app instance

Write code to import express and create an Express app instance called app.

Express

const express = require('express');
// Your code here

Need a hint?

Use require('express') to import Express and then call express() to create the app.

2

Add JSON middleware with size limit

Add the JSON middleware to app using express.json() with the option { limit: '100kb' }.

Express

const express = require('express');
const app = express();
// Your code here

Need a hint?

Use app.use() to add the JSON middleware with the limit option set to '100kb'.

3

Create POST route at /data

Create a POST route on app at path /data that sends a 200 status response with res.send('OK').

Express

const express = require('express');
const app = express();
app.use(express.json({ limit: '100kb' }));
// Your code here

Need a hint?

Use app.post('/data', (req, res) => { ... }) to create the route and respond with res.send('OK').

4

Start server on port 3000

Add code to start the Express server listening on port 3000 using app.listen(3000).

Express

const express = require('express');
const app = express();
app.use(express.json({ limit: '100kb' }));
app.post('/data', (req, res) => {
  res.send('OK');
});
// Your code here

Need a hint?

Use app.listen(3000) to start the server on port 3000.