Express.js res.sendFile() Function

Difficulty Level : Basic
Last Updated : 03 Sep, 2021

The res.sendFile() function basically transfers the file at the given path and it sets the Content-Type response HTTP header field based on the filename extension.
Syntax:

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

Parameter: The path parameter describes the path and the options parameter contains various properties like maxAge, root, etc and fn is the callback function.
Returns: It returns an Object.
Installation of express module:

You can visit the link to Install express module. You can install this package by using this command.

npm install express

After installing the express module, you can check your express version in command prompt using the command.

npm version express

After that, you can just create a folder and add a file for example, index.js. To run this file you need to run the following command.

node index.js

Example 1: Filename: index.js

javascript

var express = require('express');
var app = express();
var path = require('path');
var PORT = 3000;
 
// Without middleware
app.get('/', function(req, res){
    var options = {
        root: path.join(__dirname)
    };
     
    var fileName = 'Hello.txt';
    res.sendFile(fileName, options, function (err) {
        if (err) {
            next(err);
        } else {
            console.log('Sent:', fileName);
        }
    });
});
 
app.listen(PORT, function(err){
    if (err) console.log(err);
    console.log("Server listening on PORT", PORT);
});

Now, create a .txt file like here we have created Hello.txt in the root directory of project with the following text:

Greetings from GeeksforGeeks

Steps to run the program:

Make sure you have installed express module using the following command:

npm install express

Run index.js file using below command:

node index.js

Output:

Server listening on PORT 3000

Now open browser and go to http://localhost:3000/, now check your console and you will see the following output:

Server listening on PORT 3000
Sent: Hello.txt

And on screen you will see the following output:

Greetings from GeeksforGeeks

Example 2: Filename: index.js

javascript

var express = require('express');
const path = require('path');
var app = express();
var PORT = 3000;
 
// With middleware
app.use('/', function(req, res, next){
    
    var options = {
        root: path.join(__dirname)
    };
     
    var fileName = 'GeeksforGeeks.txt';
    res.sendFile(fileName, options, function (err) {
        if (err) {
            next(err);
        } else {
            console.log('Sent:', fileName);
            next();
        }
    });
});
 
app.get('/', function(req, res){
    console.log("File Sent")
    res.send();
});
 
app.listen(PORT, function(err){
    if (err) console.log(err);
    console.log("Server listening on PORT", PORT);
});

Make sure you create a .txt file like here we have created GeeksforGeeks.txt in the root directory of project with the following text:

Welcome from GeeksforGeeks

Run index.js file using below command:

node index.js

Now open the browser and go to http://localhost:3000/, now check your console and you will see the following output:

Server listening on PORT 3000
Sent: GeeksforGeeks.txt
File Sent

And you will see the following output on your browser screen:

Welcome from GeeksforGeeks

Reference: https://expressjs.com/en/5x/api.html#res.sendFile

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