login.html

<script
	src="https://code.jquery.com/jquery-2.2.4.min.js"
	integrity="sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44="
	crossorigin="anonymous"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/materialize/0.97.1/css/materialize.min.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/materialize/0.97.1/js/materialize.min.js"></script>
<h4 align='center' style="margin-top:75; margin-bottom:15">Login</h4>
<h6 align='center' style="color: #d3d3d3;; margin-bottom: 30;">The Classic Way!</h6>
<div id="user-login" class="row" style="max-width:750">
	<div class="col s12 z-depth-6 card-panel">
		<form class="login-form" method="post">
			<div class="row margin">
				<div class="input-field col s12">
					<i class="mdi-social-person-outline prefix"></i>
					<input class="validate" id="user_email" type="email" placeholder="Username">
				</div>
			</div>
			<div class="row margin">
				<div class="input-field col s12">
					<i class="mdi-action-lock-outline prefix"></i>
					<input id="user_pass" placeholder="Password" type="password">
				</div>
			</div>
			<div class="row">
				<div class="input-field col s12">
					<a class="btn waves-effect waves-light col s12" onclick="onButtonClick()">Login</a>
				</div>
            </div>
            <h6 style="margin-top:30;" align='center'>New Here? <a href='./register.html'>Register here</a></h6>

		</form>
	</div>
</div>

<script>
function onButtonClick(){
	// var myHeaders = new Headers();
	// myHeaders.append("Content-Type", "application/json; charset=UTF-8");
	var myHeaders = {
		'Accept': 'application/json',
  	'Content-Type': 'application/json'
	}
	//
	// var formdata = new FormData();
	// formdata.append("username", "vedangj");
	// formdata.append("password", "pass123");

	var requestOptions = {
	  method: 'POST',
	  headers: myHeaders,
	  body:JSON.stringify({
			username:"vedangj",
			password:"pass123"
		}),
	  redirect: 'follow'
	};


	fetch("http://127.0.0.1:5000/login", requestOptions)
	  .then(response => response.text())
	  .then(result => document.cookie = "subjects="+result)
	  .catch(error => console.log('error', error));
}
</script>