machinecat520
/
zj-Exercise


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #box1 {
            width: 100px;
            height: 100px;
            background-color: red;
            position: absolute;
        }
    </style>
    <script>

        //使div可以根据不同的方向键向不同的方向移动
        /**
         * 按左键，div向左移
         * 按右键，div向右移
         * 按上键，div向上移
         * 按下键，div向下移
        */
        window.onload = function () {
            //为document绑定一个按键按下的事件
            document.onkeydown = function (event) {
                event = event || window.event;       
                //定义一个移动速度的变量
                var speed = 10;
                //当用户按了Ctrl以后，速度加快
                if(event.ctrlKey){
                    speed = 50;
                };
                // console.log(event.keyCode);
                switch (event.keyCode) {
                    case 37:
                        // alert('向左');//left值减小
                        box1.style.left = box1.offsetLeft - speed + 'px';
                        break;
                    case 38:
                        // alert('向上');//top值减小
                        box1.style.top = box1.offsetTop - speed +'px';
                        break;
                    case 39:
                        // alert('向右');//left值增加
                        box1.style.left = box1.offsetLeft + speed +'px';
                        break;
                    case 40:
                        // alert('向下');//top值增加
                        box1.style.top = box1.offsetTop + speed + 'px';
                        break;
                };
            };
        };

    </script>
</head>

<body>
    <div id="box1"></div>
</body>

</html>