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JS实现用键盘控制DIV上下左右+放大缩小与变色

　　本文标签：键盘,控制DIV

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 
<title>用键盘控制DIV</title> 
<style type="text/css"> 
html,body{overflow:hidden;} 
body{margin:0;padding:0;} 
pre{color:green;padding:10px 15px;background:#f0f0f0;border:1px dotted #333;font:12px/1.5 Courier New;margin:12px;} 
span{color:#999;} 
#box{position:absolute;top:50px;left:300px;width:100px;height:100px;background:red;} 
</style> 
<script type="text/javascript"> 
window.onload = function () 
{ 
var oBox = document.getElementById("box"); 
var bLeft = bTop = bRight = bBottom = bCtrlKey = false;

setInterval(function () 
{ 
if (bLeft) 
{ 
oBox.style.left = oBox.offsetLeft - 10 + "px" 
} 
else if (bRight) 
{ 
oBox.style.left = oBox.offsetLeft + 10 + "px" 
}

if (bTop) 
{ 
oBox.style.top = oBox.offsetTop - 10 + "px" 
} 
else if(bBottom) 
{ 
oBox.style.top = oBox.offsetTop + 10 + "px" 
} 
//防止溢出 
limit(); 
},30);

document.onkeydown = function (event) 
{ 
var event = event || window.event; 
bCtrlKey = event.ctrlKey;

switch (event.keyCode) 
{ 
case 37: 
bLeft = true; 
break; 
case 38: 
if(bCtrlKey) 
{ 
var oldWidth = oBox.offsetWidth; 
var oldHeight = oBox.offsetHeight;

oBox.style.width = oBox.offsetWidth * 1.5 + "px"; 
oBox.style.height = oBox.offsetHeight * 1.5 + "px";

oBox.style.left = oBox.offsetLeft - (oBox.offsetWidth - oldWidth) / 2 + "px"; 
oBox.style.top = oBox.offsetTop - (oBox.offsetHeight - oldHeight) / 2 + "px";

break; 
} 
bTop = true; 
break; 
case 39: 
bRight = true; 
break; 
case 40: 
if(bCtrlKey) 
{ 
var oldWidth = oBox.offsetWidth; 
var oldHeight = oBox.offsetHeight;

oBox.style.width = oBox.offsetWidth * 0.75 + "px"; 
oBox.style.height = oBox.offsetHeight * 0.75 + "px";

oBox.style.left = oBox.offsetLeft - (oBox.offsetWidth - oldWidth) / 2 + "px"; 
oBox.style.top = oBox.offsetTop - (oBox.offsetHeight - oldHeight) / 2 + "px";

break; 
} 
bBottom = true; 
break; 
case 49: 
bCtrlKey && (oBox.style.background = "green"); 
break; 
case 50: 
bCtrlKey && (oBox.style.background = "yellow"); 
break; 
case 51: 
bCtrlKey && (oBox.style.background = "blue"); 
break; 
}

return false 
}; 
document.onkeyup = function (event) 
{ 
switch ((event || window.event).keyCode) 
{ 
case 37: 
bLeft = false; 
break; 
case 38: 
bTop = false; 
break; 
case 39: 
bRight = false; 
break; 
case 40: 
bBottom = false; 
break; 
} 
}; 
//防止溢出 
function limit() 
{ 
var doc = [document.documentElement.clientWidth, document.documentElement.clientHeight] 
//防止左侧溢出 
oBox.offsetLeft <=0 && (oBox.style.left = 0); 
//防止顶部溢出 
oBox.offsetTop <=0 && (oBox.style.top = 0); 
//防止右侧溢出 
doc[0] - oBox.offsetLeft - oBox.offsetWidth <= 0 && (oBox.style.left = doc[0] - oBox.offsetWidth + "px"); 
//防止底部溢出 
doc[1] - oBox.offsetTop - oBox.offsetHeight <= 0 && (oBox.style.top = doc[1] - oBox.offsetHeight + "px") 
} 
}; 
</script> 
</head> 
<body> 
<pre> 
红色方块为键盘操作区域，您可以进行如下操作： 
上：↑ 下：↓ 左：← 右：→ 
Ctrl + 1 : 背景变为绿色 
Ctrl + 2 : 背景变为黄色 
Ctrl + 3 : 背景变为蓝色 
Ctrl + ↑ : 放大 
Ctrl + ↓ : 缩小 
</pre> 
<div id="box"></div> 
</body> 
</html>

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