JavaScript學習（三十六）—移動的小球
代碼如下：
<!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>
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
#ball {
width: 200px;
height: 200px;
background-color: green;
border-radius: 50%;
position: fixed;
left: 0;
top: 0;
}
</style>
</head>
<body>
<div id="ball"></div>
<script>
var ball = document.getElementById("ball");
var i = 10;
document.onkeydown = function(e) {
//利用getStyle方法獲取當前的left和top
var divLeft = parseInt(getStyle(ball, 'left'));
var divTop = parseInt(getStyle(ball, 'top'));
//獲取事件物件
e = e || window.event;
var code = e.keyCode;
switch (code) {
case 37:
ball.style.left = divLeft - i + 'px';
break;
case 39:
ball.style.left = divLeft + i + 'px';
break;
case 38:
ball.style.top = divTop - i + 'px';
break;
case 40:
ball.style.top = divTop + i + 'px';
}
}
//定義方法，獲取CSS樣式
function getStyle(ele, cssName) {
if (ele.currentStyle == undefined) {
return window.getComputedStyle(ele, null)[cssName];
} else {
return ele.currentStyle[cssName];
}
}
</script>
</body>
</html>
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標籤：其他