Express.js res.attachment() Function

The res.attachment() function is used to set the HTTP response Content-Disposition header field to ‘attachment’. If the name of the file is given as filename, then it sets the Content-Type based on the extension name through res.type() function and finally sets the Content-Disposition ‘filename = ‘ parameter.
Syntax:

res.attachment( [filename] )

Parameter: The filename parameter describes the name of the file.
Return Value: 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 PORT = 3000;

// Without middleware
app.get('/', function(req, res){
    res.attachment('Hello.txt');
    console.log(res.get('Content-Disposition'));
});

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

Place any file in root directory of the project which can be attached, like here we have used Hello.txt.
Steps to run the program:

1. The project structure will look like this: 
   

• 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

• Open your browser and go to http://localhost:3000/, now you can see the following output on your console: 

Server listening on PORT 3000
attachment; filename="Hello.txt"

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