正文
案例:简易的Div拖拽
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案例:简易的Div拖拽
鼠标移入Div区域后,按下鼠标左键,可以拖动Div移动;松开鼠标左键,Div拖动停止。同时要求Div不能拖出屏幕显示区域外。
拖拽原理:距离不变、三个事件(onmousedown、onmousemove、onmouseup)
解决问题:
1、拖拽过程中,鼠标容易滑出Div区块;
2、防止Div拖出页面:修正位置;
3、解除绑定事件:鼠标左键抬起后,Div不再随着鼠标移动而发生位置变化;
<!DOCTYPE html>
<html lang="zh-CN"><head>
<meta charset="UTF-8">
<title>习题-拖拽Div滑块</title>
<style>
* {
margin: 0;padding: 0;
}
div {
width: 100px;
height: 100px;
margin-bottom: 0px;
background-color: purple;
position: absolute;
}
</style>
<script> window.onload = function () {
//此处写代码
} </script>
</head>
<body>
<div id='div1'></div>
</body>
</html>
参考代码:
function getPos(ev) {
var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
var scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft;
return { x: ev.clientX + scrollTop, y: ev.clientY + scrollLeft };
}
var oDiv = document.getElementById('div1');
var disX = 0;
var disY = 0;
oDiv.onmousedown = function (ev) {
var oEvent = ev || event;
disX = getPos(oEvent).x - oDiv.offsetLeft;
disY = getPos(oEvent).y - oDiv.offsetTop;
document.onmousemove = function (ev) {
var oEvent = ev || event;
var l = oEvent.clientX - disX;
var t = oEvent.clientY - disY;
if (l < 0) {
l = 0;
} else if (l > document.documentElement.clientWidth - oDiv.offsetWidth) {
l = document.documentElement.clientWidth - oDiv.offsetWidth;
}
if (t < 0) {
t = 0;
} else if (t > document.documentElement.clientHeight - oDiv.offsetHeight) {
t = document.documentElement.clientHeight - oDiv.offsetHeight;
}
oDiv.style.left = l + 'px';
oDiv.style.top = t + 'px';
}
document.onmouseup = function () {
document.onmousemove = null;
document.onmouseup = null;
}
return false;
}