function newToast(Header, Body) {
    var toast = {}
    toast.Header = Header
    toast.Body = Body
    toast.Hide = function() {
        // todo, hide
    }

    var header = document.getElementById("t-header")
    var body = document.getElementById("t-body")
    header.innerHTML = toast.Header
    body.innerHTML = toast.Body

    $('.toast').toast('show');
    return toast
}

let toast = newToast("Header Test", "Body Test")

<div class="toast" data-autohide="false" role="alert" aria-live="assertive" aria-atomic="true" data-delay=3000 id="toast">

<script>
      $(document).ready(function() {
        $(".toast").toast("show");
      });
    </script>