问拖放dataTransfer.getData总是得到空字符串

EN

import React from "react";

class Abc extends React.Component {
  drag(ev) {
    ev.dataTransfer.setData("text", ev.target.id);
  }

  allowDrop(ev) {
    ev.preventDefault();
  }

  drop(ev) {
    ev.preventDefault();
    var data = ev.dataTransfer.getData("text");
    console.log("data", data);
  }
  render() {
    return (
      <>
        <div id={"some_id"} onDragStart={this.drag} draggable={true}>
          Drag Me
        </div>

        <div onDragOver={this.allowDrop} onDrop={this.drop}>
          Drop On me
        </div>
      </>
    );
  }
}

export default Abc;