Sometimes, we want to let users download files within our Express app.
In this article, we’ll look at how to let users download files from Express apps.
res.download
One way to let users download a file from a Node.js server is to use the res.download method available with Express.
For instance, we can write:
const express = require('express')
const app = express()
const port = 3000
app.get('/', (req, res) => {
res.send('Hello World!')
})
app.get('/download', (req, res) => {
const file = `${__dirname}/download/foo.txt`;
res.download(file);
});
app.listen(port, () => {
console.log(`Example app listening at http://localhost:${port}`)
})
We just specify the path to the file with the file string variable.
Then we pass that to the res.download method to download the file.
__dirname is the current working directory of the Express app.
Serve Files as Static Files
We can also use the express.static middleware to serve a folder in our server as a static files folder.
To do this, we write:
const express = require('express')
const app = express()
const port = 3000
app.use('/download', express.static('download'))
app.get('/', (req, res) => {
res.send('Hello World!')
})
app.listen(port, () => {
console.log(`Example app listening at http://localhost:${port}`)
})
We call app.use to use the Express static middleware.
The first argument is the path that the user uses to access the static folder’s content.
And the 2nd argument is the Express static middleware.
We create the middleware by calling express.static with the folder path string.
Therefore, we serve the download folder in our server as the static folder.
res.attachment
We can also return a file as a response in our route with the route.attachment method.
It takes the same argument as the res.download method.
It sets the Content-Disposition response header to attachment .
And it also sets the Content-Type response header according to the file type being downloaded.
For instance, we can write:
const express = require('express')
const app = express()
const port = 3000
app.get('/', (req, res) => {
res.send('Hello World!')
})
app.get('/download', (req, res) => {
const file = `${__dirname}/download/foo.txt`;
res.attachment(file).send();
});
app.listen(port, () => {
console.log(`Example app listening at http://localhost:${port}`)
})
We call res.attachment with send to send the file download response to the user.
Conclusion
There’re several ways we can use to let users download files to user’s device via an Express endpoint.
