js实现键盘控制DIV移动的方法

本文实例讲述了js实现键盘控制DIV移动的方法。分享给大家供大家参考。具体分析如下：

css样式部分：

<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>

js部分：

<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>

说明：

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

html部分：

被移动的方块【DIV】

<div id="box"></div>

希望本文所述对大家的javascript程序设计有所帮助。