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In this article, we will learn how to send files to the client in Node.js using Express.

Sending files using Express in Node.js

Express.js or Express is a backend web utility framework for Node.js. Express is a Node.js web application framework that provides a powerful feature set for web and mobile applications.

The function res.sendFile() passes the file in the specified path and sets the HTTP header field of the Content-Type response according to the file extension.

grammar:

res.sendFile(path [, options] [, fn])

Follow the instructions below to send the file to the client.

Full source code - index.js :

const express = require('express');
const app = express();
const path = require('path');
const PORT = 3001;

app.get('/', (req, res, next) => {
    const fileName = 'helloworld.txt';
    res.sendFile(fileName, {root: path.join(__dirname)}, (err) => {
        if (err) {
            next(err);
        } else {
            console.log('File Sent:', fileName);
        }
    });
});

app.listen(PORT, (err) => {
    if (err) console.log(err);
    console.log("Server listening on PORT", PORT);
});

In the above example, we created a 3001server that listens to the specified port. Once the server listens to the specified port, it will execute the code in the first matching route.

sendFile()The response object will then be returned to the client via the method. If any errors are encountered, it next()will pass the errors to the error handler using the method.

If everything goes well, it returns a response object with the file contents to the client.

Try running the above code in replit with Node.js support , it will display the following result.

Output:

Server listening on PORT 3001
File Sent: helloworld.txt