HTMLElement：drag 事件

js

addEventListener("drag", (event) => {});

ondrag = (event) => {};

html

<div class="dropzone">
  <div id="draggable" draggable="true">这个 div 可以拖动</div>
</div>
<div class="dropzone" id="droptarget"></div>

css

body {
  /* Prevent the user selecting text in the example */
  user-select: none;
}

#draggable {
  text-align: center;
  background: white;
}

.dropzone {
  width: 200px;
  height: 20px;
  background: blueviolet;
  margin: 10px;
  padding: 10px;
}

.dropzone.dragover {
  background-color: purple;
}

.dragging {
  opacity: 0.5;
}

js

let dragged;

/* 在可拖动的目标上触发的事件 */
const source = document.getElementById("draggable");
source.addEventListener("drag", (event) => {
  console.log("dragging");
});

source.addEventListener("dragstart", (event) => {
  // 保存被拖动元素的引用
  dragged = event.target;
  // 设置为半透明
  event.target.classList.add("dragging");
});

source.addEventListener("dragend", (event) => {
  // 拖动结束，重置透明度
  event.target.classList.remove("dragging");
});

/* 在放置目标上触发的事件 */
const target = document.getElementById("droptarget");
target.addEventListener(
  "dragover",
  (event) => {
    // 阻止默认行为以允许放置
    event.preventDefault();
  },
  false,
);

target.addEventListener("dragenter", (event) => {
  // 在可拖动元素进入潜在的放置目标时高亮显示该目标
  if (event.target.classList.contains("dropzone")) {
    event.target.classList.add("dragover");
  }
});

target.addEventListener("dragleave", (event) => {
  // 在可拖动元素离开潜在放置目标元素时重置该目标的背景
  if (event.target.classList.contains("dropzone")) {
    event.target.classList.remove("dragover");
  }
});

target.addEventListener("drop", (event) => {
  // 阻止默认行为（会作为某些元素的链接打开）
  event.preventDefault();
  // 将被拖动元素移动到选定的目标元素中
  if (event.target.classList.contains("dropzone")) {
    event.target.classList.remove("dragover");
    dragged.parentNode.removeChild(dragged);
    event.target.appendChild(dragged);
  }
});