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

File Size Limits in Express

📖 Scenario: You are building a simple Express server that accepts JSON data uploads. To keep your server safe and efficient, you want to limit the size of the incoming JSON files.

🎯 Goal: Create an Express server that limits the JSON request body size to 100kb. This will prevent users from sending very large JSON payloads.

📋 What You'll Learn

Create an Express app instance called app

Set up JSON body parsing with a size limit of 100kb using express.json()

Add a POST route at /upload that responds with status 200 and message 'Upload received' when JSON is accepted

Start the server listening on port 3000

💡 Why This Matters

🌍 Real World

Limiting JSON body size is important in real-world web servers to prevent abuse and crashes from very large requests.

💼 Career

Backend developers often configure body parsers and set limits to ensure server stability and security.

1

Create Express app

Create a variable called express by requiring the 'express' module. Then create an Express app instance called app by calling express().

Express

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

Need a hint?

Use require('express') to import Express, then call it as a function to create the app.

2

Configure JSON body parser with size limit

Use app.use() to add JSON body parsing middleware with a size limit of '100kb' by calling express.json({ limit: '100kb' }).

Express

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

Need a hint?

Use express.json() with the limit option inside app.use().

3

Add POST route to accept uploads

Add a POST route at /upload using app.post('/upload', (req, res) => { ... }). Inside the handler, respond with status 200 and send the text 'Upload received'.

Express

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

Need a hint?

Use app.post with the path '/upload' and send a 200 status with the message inside the callback.

4

Start the server on port 3000

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

Express

const express = require('express');
const app = express();
app.use(express.json({ limit: '100kb' }));
app.post('/upload', (req, res) => {
  res.status(200).send('Upload received');
});
// Your code here

Need a hint?

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