Untitled

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Login Form</title>
<link rel="stylesheet" type="text/css" href="projet_htmlcss">
</head>
<body class="lg">
<div class="bgimg">
<div class="center">
<img src="images.png" id="profil">
<h2>User Login</h2>
<form method="post" action="" onclick="displayAlert()">
<div>
<input type="text" name="username" class="inputbox" placeholder="User Name" id="id_username">
</div>
<br>
<div>
<input type="password" name="password" class="inputbox" placeholder="User Password" id="id_password">
</div>
<br>
<div>
<button type="submit" id="">Login</button>
</div>
<div class="fp">
<button type="submit">Forget Password ?</button>
</div>
</form>
</div>
</div>
<script>
function validateform() {
var username = document.getElementById("id_username").value;
var password = document.getElementById("id_password").value;
if (username && password) {
window.location.assign ("adminpg.html");
}
else{
alert("please fill the username and password correctly");
return false;
}
}
</script>
</body>
</html>