键盘事件练习——移动的方块

<!DOCTYPE html>
<html>

    <head>
        <meta charset="utf-8" />
        <title></title>
        <style type="text/css">
            * {
                margin: 0;
                padding: 0;
            }
        </style>
    </head>

    <body style="position: relative;">
        <div id="box" style="width: 100px;height: 100px;background-color: sandybrown;position: absolute;">

        </div>
        <script type="text/javascript">


            /*获取浏览器的最大化尺寸*/
            var wi = document.documentElement.clientWidth - 100; //取得浏览器页面可视区域的宽度,（并且需要减去 方块的宽度）
            var hi = document.documentElement.clientHeight - 100; //取得浏览器页面可视区域的高度，（并且需要减去 方块的高度）

            var box = document.getElementById("box")

            document.addEventListener("keydown", function(e) {

                var l = parseInt(window.getComputedStyle(box, null).left); //获取方块坐标
                var t = parseInt(window.getComputedStyle(box, null).top);

                console.log(l, t)
                var event = e || window.event
                if(event.key == "w" & t > 0) {
                    box.style.top = t - 10 + "px";
                };
                if(event.key == "s" & t < hi) {
                    box.style.top = t + 10 + "px";
                };
                if(event.key == "a" & l > 0) {
                    box.style.left = l - 10 + "px";
                };
                if(event.key == "d" & l < wi) {
                    box.style.left = l + 10 + "px";
                };
            }, false)
        </script>
    </body>

</html>