let source, drop;
function initiate() {
  source = document.getElementById("image");
  source.addEventListener("dragstart", dragged);
  drop = document.getElementById("dropbox");
  drop.addEventListener("dragenter", function(event) {
    event.preventDefault();
  });
  drop.addEventListener("dragover", function(event) {
    event.preventDefault();
  });
  drop.addEventListener("drop", dropped);
}
function dragged(event) {
  const code = '<img src="' + source.src + '">';
  event.dataTransfer.setData("Text", code);
}
function dropped(event) {
  event.preventDefault();
  drop.innerHTML = event.dataTransfer.getData("Text");
}
window.addEventListener("DOMContentLoaded", initiate);