js拖拽效果 js面向对象方式实现拖拽效果

时间:2021-03-03 web前端的清流人气:0

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拖拽功能的实现原理：（直接拿走！）

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    #box {
      position: absolute;
      left: 100px;
      top: 100px;
      width: 100px;
      height: 100px;
      background: red;
    }

    #box2 {
      position: absolute;
      left: 200px;
      top: 200px;
      width: 100px;
      height: 100px;
      background: green;
    }
  </style>
</head>

<body>
  <div id="box">文字</div>
  <div id="box2">文字</div>
</body>
<script>
  class Drag {
    startMouse = {};
    startEl = {};
    #el = null;
    constructor(el, option) {
      this.#el = el;
      this.option = option;
      this.start();
    }
    start() {
      let move = (e) => {
        this.move(e)
      }
      this.#el.addEventListener('mousedown', (e) => {
        this.startMouse = {
          x: e.clientX,
          y: e.clientY,
        }
        this.ondragstart && this.ondragstart(e)
        this.startEl = this.getOffset();
        document.addEventListener('mousemove', move);
        document.addEventListener('mouseup', (e) => {
          document.removeEventListener('mousemove', move);
          this.end(e);
        }, {
          once: true
        })
        e.preventDefault();

      })
    }
    move(e) {
      let nowMouse = {
        x: e.clientX,
        y: e.clientY,
      }
      let disMouse = {
        x: nowMouse.x - this.startMouse.x,
        y: nowMouse.y - this.startMouse.y
      }
      this.ondrag && this.ondrag(e)
      this.setOffset(disMouse)
    }
    end(e) {
      this.ondragend && this.ondragend(e)
    }
    getOffset() {
      return {
        x: parseFloat(getComputedStyle(this.#el)["left"]),
        y: parseFloat(getComputedStyle(this.#el)["top"])
      }
    }
    setOffset(dis) {
      this.#el.style.left = this.startEl.x + dis.x + 'px'
      this.#el.style.top = this.startEl.y + dis.y + 'px'
    }
  }
  let box = document.querySelector("#box");
  let box2 = document.querySelector("#box2");
  let d = new Drag(box);
  let d2 = new Drag(box2);
  let clonex = null;
  d2.ondragstart = (e) => {
    clonex = box2.cloneNode(true);
    document.body.appendChild(clonex)
    box2.style.opacity = 0.5
  }
  d2.ondragend = () => {
    document.body.removeChild(clonex);
    box2.style.opacity = 1
  }
</script>

</html>

最终效果（拖动的为绿色块）

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