-tıklandığında whatsapp numarasında yönlendirmektedir. basit ama geliştirmek isteyenlere fikir olabilir.




<!doctype html>
<html>
 <head>
 <!-- Bootstrap CSS -->
 <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" >
  <!-- Fontawesome  CSS -->
 <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
 <script src="https://cdnjs.cloudflare.com/ajax/libs/lazysizes/5.1.0/lazysizes.min.js" ></script>
 </head>
 <body>
 <center>
 <div class="container" style="margin:50px">
 <a href="https://wa.me/90000000text=MERHABA" title="click to open whatsapp chat"><button class="btn btn-success">
 <i class="fa fa-whatsapp"></i> Mesaj Yaz
 </button></a>
 </div>
 </center>
 </body>
</html>