JAVASCRIPT

sweetalert allow html

<script>
  Swal.fire({ 
      html: "Hello, <strong>world!</strong>"
  });
</script>

sweetalert example

//import sweetalert
<script src="https://unpkg.com/sweetalert/dist/sweetalert.min.js"></script>

//Alert
<script>swal("My title", "My description", "success");</script>

sweetalert js full code

<script>
  // when window loades this alert pop ups 
        swal({
      text: "Hello world!",
           }     );
    </script>