JS做物体的拖拽效果

示意图：

JS做物体的拖拽效果

代码：

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
div{
position: absolute;
top: 0;
left: 0;
width: 100px;
height: 100px;
background-color: cornflowerblue;

}
</style>
</head>
<body>

<div></div>
<script>
// 获取要实现拖拽的物体
var box = document.getElementsByTagName('div')[0];
// 调用函数
tuozhuai(box);

function tuozhuai(dom){
dom.onmousedown = function(e){
// 记录鼠标上一次的位置
var xLast = 0;
var yLast =0;
// 处理事件
var event = event || e;
// 记录按下时的横坐标与纵坐标
var xMouse = event.clientX;
var yMouse = event.clientY;
// 记录鼠标与物体边缘的距离，方便下一步计算移动后的top和left
var xDis = xMouse - this.offsetLeft;
var yDis = yMouse - this.offsetTop;
// 将物体记录，后面调用。减少代码的改动。
var self = this;

// 鼠标移动
document.onmousemove = function(e){
var event = event || e;
var newLeft = event.clientX - xDis;
var newTop = event.clientY -yDis;
// 鼠标移动，改变物体的left值和top值
self.style.left = newLeft + "px";
self.style.top = newTop + "px";

}

document.onmouseup = function(){
// 鼠标抬起，将事件置空
document.onmouseup = null;
document.onmousemove = null;

}
}

}

</script>
</body>

</html>

JS做物体的拖拽效果

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