How do I programmatically send a 404 response using Express? | by John Au-Yeung | November 2024

Sometimes we want to programmatically send a 404 response in our Express app.

In this article, we’ll look at how to programmatically send a 404 response in our Express app.

To programmatically send a 404 response in our Express app, we can use the res.sendStatus or res.status Methods.

For example, we can write:

const express = require('express')
const app = express()
const port = 3000app.get('/', (req, res) =>{
res.send('hello world');
});app.get('*', (req, res) => {
res.sendStatus(404);
});app.listen(port, () => {
console.log(`Example app listening at http://localhost:${port}`)
})

call sendStatus with 404 in the * Route that runs whenever a request is received from a URL that is not captured by any other route.

We can also write:

const express = require('express')
const app = express()
const port = 3000app.get('/', (req, res) => {
res.send('hello world');
});app.get('*', (req, res) => {
res.status(404).send('Not found');
});app.listen(port, () => {
console.log(`Example app listening at http://localhost:${port}`)
})

call res.status with 404 to send a 404 response.

Then we’ll call send with 'Not Found' to ship it with a body.

To programmatically send a 404 response in our Express app, we can use the res.sendStatus or res.status Methods.