js将页面上取得的元素坐标转换为电脑屏幕坐标-CFANZ编程社区

代码：
<!DOCTYPE html>
<html>

<head>
    <title>计算屏幕坐标</title>

    <meta charset="utf-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <style type="text/css">
        body {
            margin: 0;
            padding: 0;
        }

        #msg {
            background-color: #eeeeee;
            height: 200px;
        }
    </style>
</head>

<body>
    <div id="msg"></div>

    <script type="text/javascript">
        let div = document.querySelector('#msg');
        let msg = '';
        let firstPoint = getPoint(0, 0);

        window.onresize = function (e) {
            setTimeout(() => {
                firstPoint = getPoint(0, 0);
                showPoint();
            }, 100);
        }

        window.onmousemove = function (e) {
            setTimeout(() => {
                showPoint(e);
            }, 100);
        }

        function showPoint(e) {
            msg = '';
            let point;
            if (e) {
                point = getPoint(e.clientX, e.clientY);
            } else {
                point = getPoint(0, 0);
            }

            msg += '===========================================================================================<br />';
            msg += '页面左上角屏幕坐标：' + firstPoint.x + ', ' + firstPoint.y + '<br />';
            if (e) {
                msg += '事件屏幕坐标：' + e.screenX + ', ' + e.screenY + '<br />';
                msg += '计算屏幕坐标：' + point.x + ', ' + point.y + '<br />';
                if (e.screenX == point.x && e.screenY == point.y) {
                    msg += '相等<br />';
                } else {
                    msg += '不相等<br />';
                }
            }
            div.innerHTML = msg;
        }

        //计算屏幕坐标
        function getPoint(clientX, clientY) {
            let left = 0;
            let top = 0;

            if (window.outerWidth + 16 == window.innerWidth && window.outerHeight + 16 == window.innerHeight) { //最大化全屏
                msg += '最大化全屏状态<br />';
                top = (window.outerHeight - window.innerHeight + 8) + window.screenTop + clientY;
                left = (window.outerWidth - window.innerWidth + 8) + window.screenLeft + clientX;
            } else if (window.outerWidth == window.innerWidth && window.outerHeight == window.innerHeight) { //全屏
                msg += '全屏状态<br />';
                top = (window.outerHeight - window.innerHeight) + window.screenTop + clientY;
                left = (window.outerWidth - window.innerWidth) + window.screenLeft + clientX;
            }
            else {
                if (window.outerWidth == screen.availWidth && window.outerHeight == screen.availHeight) { //最大化
                    msg += '最大化状态<br />';
                    top = (window.outerHeight - window.innerHeight) + window.screenTop + clientY;
                    left = (window.outerWidth - window.innerWidth) + window.screenLeft + clientX;
                } else {
                    msg += '非最大化非全屏状态<br />';
                    top = (window.outerHeight - window.innerHeight - 8) + window.screenTop + clientY;
                    left = (window.outerWidth - window.innerWidth - 8) + window.screenLeft + clientX;
                }
            }

            return { x: left, y: top };
        }
    </script>

</body>

</html>
View Code
说明：适用于谷歌浏览器，360浏览器下有BUG，因为360浏览器有状态栏。
思考：获取电脑屏幕坐标的意义是什么？