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How to send an email in Node.js?

The Nodemailer Module

The Nodemailer module makes it easy to send emails from your computer.

The Nodemailer module can be downloaded and installed using npm:C:\Users\Your Name>npm install nodemailer

After you have downloaded the Nodemailer module, you can include the module in any application:var nodemailer = require(‘nodemailer’);


Send an Email

Now you are ready to send emails from your server.

Use the username and password from your selected email provider to send an email. This tutorial will show you how to use your Gmail account to send an email:

Example

var nodemailer = require(‘nodemailer’);

var transporter = nodemailer.createTransport({
  service: ‘gmail’,
  auth: {
    user: ‘youremail@gmail.com‘,
    pass: ‘yourpassword
  }
});

var mailOptions = {
  from: ‘youremail@gmail.com‘,
  to: ‘myfriend@yahoo.com‘,
  subject: ‘Sending Email using Node.js’,
  text: ‘That was easy!’
};

transporter.sendMail(mailOptions, function(error, info){
  if (error) {
    console.log(error);
  } else {
    console.log(‘Email sent: ‘ + info.response);
  }
});

And that’s it! Now your server is able to send emails.



Multiple Receivers

To send an email to more than one receiver, add them to the “to” property of the mailOptions object, separated by commas:

Example

Send email to more than one address:var mailOptions = {
  from: ‘youremail@gmail.com’,
  to: myfriend@yahoo.commyotherfriend@yahoo.com,
  subject: ‘Sending Email using Node.js’,
  text: ‘That was easy!’
}


Send HTML

To send HTML formatted text in your email, use the “html” property instead of the “text” property:

Example

Send email containing HTML:var mailOptions = {
  from: ‘youremail@gmail.com’,
  to: ‘myfriend@yahoo.com‘,
  subject: ‘Sending Email using Node.js’,
  html: ‘<h1>Welcome</h1><p>That was easy!</p>’
}

How Node.js Upload Files?

The Formidable Module

There is a very good module for working with file uploads, called “Formidable”.

The Formidable module can be downloaded and installed using NPM:C:\Users\Your Name>npm install formidable

After you have downloaded the Formidable module, you can include the module in any application:var formidable = require(‘formidable’);


Upload Files

Now you are ready to make a web page in Node.js that lets the user upload files to your computer:

Step 1: Create an Upload Form

Create a Node.js file that writes an HTML form, with an upload field:

Example

This code will produce an HTML form:var http = require(‘http’);

http.createServer(function (req, res) {
  res.writeHead(200, {‘Content-Type’: ‘text/html’});
  res.write(‘<form action=”fileupload” method=”post” enctype=”multipart/form-data”>’);
  res.write(‘<input type=”file” name=”filetoupload”><br>’);
  res.write(‘<input type=”submit”>’);
  res.write(‘</form>’);
  return res.end();
}).listen(8080);

Step 2: Parse the Uploaded File

Include the Formidable module to be able to parse the uploaded file once it reaches the server.

When the file is uploaded and parsed, it gets placed on a temporary folder on your computer.

Example

The file will be uploaded, and placed on a temporary folder:var http = require(‘http’);
var formidable = require(‘formidable’);

http.createServer(function (req, res) {
  if (req.url == ‘/fileupload’) {
    var form = new formidable.IncomingForm();
    form.parse(req, function (err, fields, files) {
      res.write(‘File uploaded’);
      res.end();
    });
  } else {
    res.writeHead(200, {‘Content-Type’: ‘text/html’});
    res.write(‘<form action=”fileupload” method=”post” enctype=”multipart/form-data”>’);
    res.write(‘<input type=”file” name=”filetoupload”><br>’);
    res.write(‘<input type=”submit”>’);
    res.write(‘</form>’);
    return res.end();
  }
}).listen(8080);



Step 3: Save the File

When a file is successfully uploaded to the server, it is placed on a temporary folder.

The path to this directory can be found in the “files” object, passed as the third argument in the parse() method’s callback function.

To move the file to the folder of your choice, use the File System module, and rename the file:

Example

Include the fs module, and move the file to the current folder:var http = require(‘http’);
var formidable = require(‘formidable’);
var fs = require(‘fs’);

http.createServer(function (req, res) {
  if (req.url == ‘/fileupload’) {
    var form = new formidable.IncomingForm();
    form.parse(req, function (err, fields, files) {
      var oldpath = files.filetoupload.path;
      var newpath = ‘C:/Users/Your Name/’ + files.filetoupload.name;
      fs.rename(oldpath, newpath, function (err) {
        if (err) throw err;
        res.write(‘File uploaded and moved!’);
        res.end();
      });
 });
  } else {
    res.writeHead(200, {‘Content-Type’: ‘text/html’});
    res.write(‘<form action=”fileupload” method=”post” enctype=”multipart/form-data”>’);
    res.write(‘<input type=”file” name=”filetoupload”><br>’);
    res.write(‘<input type=”submit”>’);
    res.write(‘</form>’);
    return res.end();
  }
}).listen(8080);

What are Node.js Events?

Node.js is perfect for event-driven applications.


Events in Node.js

Every action on a computer is an event. Like when a connection is made or a file is opened.

Objects in Node.js can fire events, like the readStream object fires events when opening and closing a file:

Example

var fs = require(‘fs’);
var rs = fs.createReadStream(‘./demofile.txt’);
rs.on(‘open’, function () {
  console.log(‘The file is open’);
});


Events Module

Node.js has a built-in module, called “Events”, where you can create-, fire-, and listen for- your own events.

To include the built-in Events module use the require() method. In addition, all event properties and methods are an instance of an EventEmitter object. To be able to access these properties and methods, create an EventEmitter object:var events = require(‘events’);
var eventEmitter = new events.EventEmitter();


The EventEmitter Object

You can assign event handlers to your own events with the EventEmitter object.

In the example below we have created a function that will be executed when a “scream” event is fired.

To fire an event, use the emit() method.

Example

var events = require(‘events’);
var eventEmitter = new events.EventEmitter();

//Create an event handler:
var myEventHandler = function () {
  console.log(‘I hear a scream!’);
}

//Assign the event handler to an event:
eventEmitter.on(‘scream’, myEventHandler);

//Fire the ‘scream’ event:
eventEmitter.emit(‘scream’);

What is NPM in Node.js?

What is NPM?

NPM is a package manager for Node.js packages, or modules if you like.

www.npmjs.com hosts thousands of free packages to download and use.

The NPM program is installed on your computer when you install Node.js

NPM is already ready to run on your computer!


What is a Package?

A package in Node.js contains all the files you need for a module.

Modules are JavaScript libraries you can include in your project.


Download a Package

Downloading a package is very easy.

Open the command line interface and tell NPM to download the package you want.

I want to download a package called “upper-case”:

Download “upper-case”:C:\Users\Your Name>npm install upper-case

Now you have downloaded and installed your first package!

NPM creates a folder named “node_modules”, where the package will be placed. All packages you install in the future will be placed in this folder.

My project now has a folder structure like this:

C:\Users\My Name\node_modules\upper-case



Using a Package

Once the package is installed, it is ready to use.

Include the “upper-case” package the same way you include any other module:var uc = require(‘upper-case’);

Create a Node.js file that will convert the output “Hello World!” into upper-case letters:

Example

var http = require(‘http’);
var uc = require(‘upper-case’);
http.createServer(function (req, res) {
  res.writeHead(200, {‘Content-Type’: ‘text/html’});
  res.write(uc(“Hello World!”));
  res.end();
}).listen(8080)

Save the code above in a file called “demo_uppercase.js”, and initiate the file:

Initiate demo_uppercase:C:\Users\Your Name>node demo_uppercase.js

If you have followed the same steps on your computer, you will see the same result as the example: http://localhost:8080

What is Node.js HTTP Module?

The Built-in HTTP Module

Node.js has a built-in module called HTTP, which allows Node.js to transfer data over the Hyper Text Transfer Protocol (HTTP).

To include the HTTP module, use the require() method:var http = require(‘http’);


Node.js as a Web Server

The HTTP module can create an HTTP server that listens to server ports and gives a response back to the client.

Use the createServer() method to create an HTTP server:

Example

var http = require(‘http’);

//create a server object:
http.createServer(function (req, res) {
  res.write(‘Hello World!’); //write a response to the client
  res.end(); //end the response
}).listen(8080); //the server object listens on port 8080

The function passed into the http.createServer() method, will be executed when someone tries to access the computer on port 8080.

Save the code above in a file called “demo_http.js”, and initiate the file:

Initiate demo_http.js:C:\Users\Your Name>node demo_http.js

If you have followed the same steps on your computer, you will see the same result as the example: http://localhost:8080



Add an HTTP Header

If the response from the HTTP server is supposed to be displayed as HTML, you should include an HTTP header with the correct content type:

Example

var http = require(‘http’);
http.createServer(function (req, res) {
  res.writeHead(200, {‘Content-Type’: ‘text/html’});
  res.write(‘Hello World!’);
  res.end();
}).listen(8080);

The first argument of the res.writeHead() method is the status code, 200 means that all is OK, the second argument is an object containing the response headers.


Read the Query String

The function passed into the http.createServer() has a req argument that represents the request from the client, as an object (http.IncomingMessage object).

This object has a property called “url” which holds the part of the url that comes after the domain name:

demo_http_url.jsvar http = require(‘http’);
http.createServer(function (req, res) {
  res.writeHead(200, {‘Content-Type’: ‘text/html’});
  res.write(req.url);
  res.end();
}).listen(8080);

Save the code above in a file called “demo_http_url.js” and initiate the file:

Initiate demo_http_url.js:C:\Users\Your Name>node demo_http_url.js

If you have followed the same steps on your computer, you should see two different results when opening these two addresses:

http://localhost:8080/summer

Will produce this result:/summerRun example »

http://localhost:8080/winter

Will produce this result:/winter


Split the Query String

There are built-in modules to easily split the query string into readable parts, such as the URL module.

Example

Split the query string into readable parts:var http = require(‘http’);
var url = require(‘url’);

http.createServer(function (req, res) {
  res.writeHead(200, {‘Content-Type’: ‘text/html’});
  var q = url.parse(req.url, true).query;
  var txt = q.year + ” ” + q.month;
  res.end(txt);
}).listen(8080);

Save the code above in a file called “demo_querystring.js” and initiate the file:

Initiate demo_querystring.js:C:\Users\Your Name>node demo_querystring.js

The address: http://localhost:8080/?year=2017&month=July

Will produce this result:2017 July