作业分析
鼠标拖拽 2025-03-23 220916.png
代码示例
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>鼠标拖拽</title>
<style>
#box{
width: 300px;
height: 200px;
background-color: antiquewhite;
position: absolute;
}
</style>
</head>
<body>
<div id="box"></div>
<script>
//获取要操作的标签对象
let box = document.getElementById("box")
//事件1：鼠标位置1按下，获取offsetX/offsetY
box.onmousedown = function (e){
//获取鼠标在div上的位置
let ox = e.offsetX
let oy = e.offsetY
//事件2：鼠标在网页中移动（包含在事件1中）
document.onmousemove = function(e2){
//获取鼠标在浏览器窗口中的位置
let cx = e2.clientX
let cy = e2.clientY
//计算left和top
let _left = cx - ox
let _top = cy - oy
//边界判断
//左边界
if(_left < 0){
_left = 0
}
//上边界
if(_top < 0){
_top = 0
}
//右边界
if(_left > document.documentElement.clientWidth - box.offsetWidth){
_left = document.documentElement.clientWidth - box.offsetWidth
}
//下边界
if(_top > document.documentElement.clientHeight - box.offsetHeight){
_top = document.documentElement.clientHeight - box.offsetHeight
}
//给div设置位置
box.style.left = _left + "px"
box.style.top = _top + "px"
}
//事件3：和事件1平行关系，网页中松开鼠标-停止移动
document.onmouseup = function(){
//停止移动
document.onmousemove = null
}
}
</script>
</body>
</html>
