Some times we need to verify the user accessing our web app. Email verification is one of the reliable verification processes. It includes the following steps: 1. User will register his/her email id along with his/her other details with a suitable password. 2. The Web App will collect and store the user details and send back an email with a clickable link to that email id. When that link is clicked his/her identity will be verified. 3. When the user clicks the email link on the browser/client application, the web app(server) will get the unique id associated with request and retrieve the user details associated with the id and compare it. If succeeds, the web app will set the proper session and respond with login successful. The browser application(client side) may be like this:

<html>
<head>
</head>
<body>
<div id='reg' class='inner' style='display: none;'>
<div class='first'>
		<input name='name' id='name' type='text' size='35' placeholder='Your name'/>
		<input name='email' id='emailid' type='text' size='35' placeholder='Email Id'/>
		<input name='pin' id='pin' type='text' size='15' placeholder='PIN Code'/>
		<input name='pass' id='passid' type='password' size='25' placeholder='Password'/>
		<input name='conf' id='confrm' type='password' size='25' placeholder='Confirm Password'/>
	</div>
	<div class='first'>
		<button name='register' id='register' onclick='registerme()' type='button'>Register</button>
		    <button name='back2' id='back2' onclick='doBackLog()' type='button'>Back</button>
	</div>
</div>
</body>
</html>

The registerme() function is implemented in javascript.

async function registerme(){
var email = document.getElementById('emailid').value;
	var name = document.getElementById('name').value;
	var pin = document.getElementById('pin').value;
	var pass = document.getElementById('passid').value;
	var conf = document.getElementById('confrm').value;
	if(pass.localeCompare(conf) !== 0){
		alert('Password mismatch');
		return;
	}
	var addMe = {};
	addMe[‘todo’] = 'newreg';
	addMe['email'] = email;
	addMe['name'] = name;
	addMe['zip'] = pin;
	addMe['pass'] = pass;
	let formData = new FormData();
	formData.append('mydata', JSON.stringify(addMe));
	let res = await fetch('/registerMe', {method: 'POST', body: formData});
	var data = await res.json();
	data = JSON.stringify(data);
	alert(data);
}

Now, when the user clicks on register button, the request will go to the web app. On the basis of user inputs, the web app will create a unique email link and send back to the user’s email id. Note: We declared the above function async, because we used await with fetch statement. await cannot be used without declaring the function async. This will cause the function to wait for the fetch results. To accomplish this, we need to create a Node js app with npm init. We need to install the libraries express, formidable, dotenv, nodemailer. So, in the Node js web app(server) we use the following code:

app.post('/registerMe', (req, res)=>{
	var form = new formidable.IncomingForm();
	form.parse(req,async (err, fields, files)=>{
		var parsed = JSON.parse(fields.mydata);
		var email = parsed.email;
		var name = parsed.name;
		var zip = parsed.zip;
		var pass = parsed.pass;
		if(parsed.todo === 'newreg') sendLink(req,res, email, name, zip, pass);
	});
});

In the sendLink function you have to replace the senders email address in the mailOptions and also replace the host address and authorization user and password in the smtpTransport var.

function sendLink(req,resp, to,name, zip, pass){
	var user = {};
	host = req.headers.host;
	//create random 16 character token
	var chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
	var vtoken = '';
	for(var i = 8; i > 0; --i){
		vtoken += chars[Math.round(Math.random()*(chars.length - 1))]
	}
	var link = 'https://'+ host + '/verify?id='+vtoken;
	var userdata = {
		token: vtoken,
		host: host,
		to: to,
		name: name,
		zip: zip,
		pass: pass
	};
	user[vtoken] = userdata;
	if(fs.existsSync(__dirname+'/abc/abc.json')){
        		var obj = fs.readFileSync(__dirname+'/abc/abc.json');
       		 var json = JSON.parse(obj);
        		var keys = Object.keys(json);
        		json[vtoken] = userdata;
        		fs.writeFileSync(__dirname+'/abc/abc.json',JSON.stringify(json), 'utf-8', (err)=>{
            			if(err){
				return logger.debug("Error occured while saving json Object in sendLink");
			}
		});
	}else{
		fs.writeFileSync('./abc/abc.json', JSON.stringify(user), 'utf-8', (err)=>{ 
			if(err){
				return logger.debug("Error occured while saving json Object");
			}
		} );
    	}
	var mailOptions = {
		from: 'xxxxxx@xxxxxx.com',
		to: to,		//req.query.to,
		subject: 'Please Confirm your Email Account',
		html: 'Hello,<br>Welcome to jeePhysicsAspirants<br>Please click on the link to Activate your Account.<br><a href='+link+'>Click here to verify</a>'
	}
	var isSend = false;
	var smtpTransport = nodemailer.createTransport({
		host: 'smtp.gmail.com',
		port: 465,
		secure: true,
		auth: {
			user: 'xxxxxx@xxxxxx.com', 
			pass: xxxxxxxxxxxxxxx   
		}
	});
	smtpTransport.sendMail(mailOptions, function(error, response){
		if(error){
			return logger.debug(error);;
		}
	});
	resp.end(JSON.stringify('Message sent, an email link has been sent to you to Activate your account'));
}

Now email activation link will be sent to the user’s mail box. When the user will click the email link the request will go to the web app(server), next the app will verify the user’s account. This is the verification process in the Nodejs web server (web app):

app.get('/verify', (req, resp)=>{
var object = url.parse(req.url, true);
	var file = JSON.parse(fs.readFileSync(__dirname+'/test/test.json'));
	var reqid = object.query.id;
	if( typeof file[reqid] === 'undefined'){
		resp.end(JSON.stringify('<h1>Bad Command</h1>'));
		return;
} 
	if(('https://'+req.headers.host) === ('https://'+file[reqid].host)){
		if(reqid === file[reqid].token){
			// here we can do our tasks related to successful verification
resp.end(JSON.stringify('<h1>Email '+usrObj[reqid].to+'has been successfully verified.</h1>'));
		}else{
			resp.end(JSON.stringify('<h1>Bad Request</h1>'));
		}
	}else{
		resp.end(JSON.stringify('<h1>Request is from unknown source.</h1>'));
}
});

So, upon successful verification the http response will show “Email yourname@yourdomain.com (your registered email id) has been successfully verified”