javascript DIV拖拽

function allowDrop(allowdropevent) {
  allowdropevent.target.style.color = "blue";
  allowdropevent.preventDefault();
}

function drag(dragevent) {
  dragevent.dataTransfer.setData("text", dragevent.target.id);
  dragevent.target.style.color = "green";
}

function drop(dropevent) {
  dropevent.preventDefault();
  const data = dropevent.dataTransfer.getData("text");
  dropevent.target.appendChild(document.getElementById(data));
  document.getElementById("drag").style.color = "black";
}