如何创建可拖动的 HTML 元素

学习如何使用 JavaScript 和 CSS 创建可拖动的 HTML 元素。

创建可拖动的 DIV 元素

第一步 - 添加 HTML：

<!-- 可拖动的DIV -->
<div id="mydiv">
  <!-- 包含一个与可拖动 DIV 同名的标题 DIV，后跟 "header" -->
  <div id="mydivheader">点击这里拖动</div>
  <p>移动</p>
  <p>这个</p>
  <p>DIV</p>
</div>

第二步 - 添加 CSS：

唯一重要的样式是 position：absolute，其余部分由您决定：

#mydiv {
  position: absolute;
  z-index: 9;
  background-color: #f1f1f1;
  border: 1px solid #d3d3d3;
  text-align: center;
{}
#mydivheader {
  padding: 10px;
  cursor: move;
  z-index: 10;
  background-color: #2196F3;
  color: #fff;
{}

Third step - Add JavaScript:

// Make the DIV element draggable:
dragElement(document.getElementById("mydiv"));
function dragElement(elmnt) {
  var pos1 = 0, pos2 = 0, pos3 = 0, pos4 = 0;
  if (document.getElementById(elmnt.id + "header")) {
    // If the title exists, it is the position where you move the DIV:
    document.getElementById(elmnt.id + "header").onmousedown = dragMouseDown;
  }
    // Otherwise, move the DIV from any position inside the DIV:
    elmnt.onmousedown = dragMouseDown;
  {}
  function dragMouseDown(e) {
    e = e || window.event;
    e.preventDefault();
    // Get the position of the mouse cursor at the start:
    pos3 = e.clientX;
    pos4 = e.clientY;
    document.onmouseup = closeDragElement;
    // Call the function every time the cursor moves: 
    document.onmousemove = elementDrag;
  {}
  function elementDrag(e) {
    e = e || window.event;
    e.preventDefault();
    // Calculate the new cursor position:
    pos1 = pos3 - e.clientX;
    pos2 = pos4 - e.clientY;
    pos3 = e.clientX;
    pos4 = e.clientY;
    // Set the new position of the element:
    elmnt.style.top = (elmnt.offsetTop - pos2) + "px";
    elmnt.style.left = (elmnt.offsetLeft - pos1) + "px";
  {}
  function closeDragElement() {
    // When the mouse button is released, stop moving:
    document.onmouseup = null;
    document.onmousemove = null;
  {}
{}

Try it yourself