js鍵盤控制DIV移動

<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]
	//防止左側溢出
oBox.offsetLeft <=0 && (oBox.style.left = 0);
	//防止頂部溢出
oBox.offsetTop <=0 && (oBox.style.top = 0);
	//防止右側溢出
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>


上：↑ 下：↓ 左：← 右：→
Ctrl + 1 : 背景變為綠色
Ctrl + 2 : 背景變為黃色
Ctrl + 3 : 背景變為藍色
Ctrl + ↑ : 放大
Ctrl + ↓ : 縮小

//被移動的方塊【DIV】
<div id="box"></div>