原生JS实现拖拽功能

时间:2020-12-16 Dreamer_xr 人气:0

这篇文章主要为大家介绍了JS实现拖拽功能，文中示例代码介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们可以参考一下

拖拽的原理：三个事件 onmousedown、onmousemove、onmousemove

1、鼠标按下，触发onmousedown，获取鼠标坐标x,y，获取元素坐标x,y

通过event.clientX、event.clientY获取鼠标位置的坐标

let x = e.clientX - box.offsetLeft; //鼠标点击坐标距离盒子左边缘的距离
let y = e.clientY - box.offsetTop; //鼠标点击坐标距离盒子上边缘的距离

2、设置元素left、top值，（元素要设置position:absolute）

box.style.left = ev.clientX - x + 'px';
box.style.top = ev.clientY - y + 'px';

3、放开鼠标取消dom事件

下面是详细代码：我只开了横向移动

<!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 {
 width: 100px;
 height: 100px;
 background: red;
 position: absolute
 }
 
 </style>
</head>
 
<body style="position: relative;overflow: hidden;">
 <div id="box">
 
 </div>
 
 <script>
 window.onload = function () {
 let box = document.getElementById('box')
 box.onmousedown = function (ev) {
 let e = ev || event;
 let x = e.clientX - box.offsetLeft; //鼠标点击坐标距离盒子左边缘的距离
 let y = e.clientY - box.offsetTop; //鼠标点击坐标距离盒子上边缘的距离
 document.onmousemove = function (ev) {
  let e = ev || event;
  box.style.left = ev.clientX - x + 'px';
  box.style.top = ev.clientY - y + 'px';
  
  let bodyScreenX = ev.screenX
  let bodyClientWidth = document.body.clientWidth
  
  document.onmouseup = function (ev) {
  if (ev.clientX - x < 0) {
  box.style.left = 0
  } else if (bodyScreenX > bodyClientWidth) {
  box.style.right = 0
  box.style.left = bodyClientWidth - 100 + 'px'
  }
  document.onmousemove = null;
  document.onmouseup = null;
  }
 }
 }
 }
 
 </script>
</body>
 
</html>

加载全部内容