原生JS实现拖拽功能
本文实例为大家分享了JS实现拖拽功能的具体代码，供大家参考，具体内容如下
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>
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