键盘事件 | 笑笑の博客

按键按下：onkeydown,当一直按的时候，第一个与第二个间隔时间会比较长，后面的间隔特别短，只是浏览器提供的防止误触
按键松开onkeyup

键盘事件一般绑定给可以获取焦点的对象或document

返回按键编码：keycode

通过方向键，控制div的移动
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>
        #box{
            height: 100px;
            width: 100px;
            position: absolute;
            background-color: green;
            align-content: center;
        }
    </style>
    <script>
        window.onload = function(){
            document.onkeydown = function(event){
                event = event || window.event;
                /*火狐：左上右下37 38 39 40
                */
                var box = document.getElementById("box");
                switch(event.keyCode){
                    case 37:
                        box.style.left = box.offsetLeft - 10 +"px";
                        break;
                    case 38:
                        box.style.top = box.offsetTop - 10 +"px";
                        break;
                    case 39:
                        box.style.left = box.offsetLeft + 10 +"px";
                        break;
                    case 40:
                        box.style.top = box.offsetTop + 10 +"px";
                }
            }
        }
    </script>
</head>
<body>
    <div id="box"></div>
</body>
</html>