DataTransferItem: kind 属性

function dropHandler(ev) {
  console.log("Drop");
  ev.preventDefault();
  for (const item of ev.dataTransfer.items) {
    if (item.kind === "string" && item.type.match("^text/plain")) {
      // This item is the target node
      item.getAsString((s) => {
        ev.target.appendChild(document.getElementById(s));
      });
    } else if (item.kind === "string" && item.type.match("^text/html")) {
      // Drag data item is HTML
      console.log("… Drop: HTML");
    } else if (item.kind === "file" && item.type.match("^image/")) {
      // Drag data item is an image file
      const f = item.getAsFile();
      console.log("… Drop: File");
    }
  }
}