javascript 用键盘控制DIV上下左右移动及放大缩小（event.keyCode及屏幕大小的用法）

在这里插入图片描述

<!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) {
						//因为30微妙执行一次，所以没30毫秒向左10px
						oBox.style.left = oBox.offsetLeft - 10 + "px"
					} else if (bRight) {
						//因为30微妙执行一次，所以没30毫秒向右10px
						oBox.style.left = oBox.offsetLeft + 10 + "px"
					}

					if (bTop) {
						//因为30微妙执行一次，所以没30毫秒向上10px
						oBox.style.top = oBox.offsetTop - 10 + "px"
					} else if (bBottom) {
						//因为30微妙执行一次，所以没30毫秒向下10px
						oBox.style.top = oBox.offsetTop + 10 + "px"
					}
					//防止溢出,到达最边缘不能前行
					limit();
				}, 30);

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

					switch (event.keyCode) {
						case 37:/* 左 */
							bLeft = true;
							break;
						case 38:/* 上 */
							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:/* 右 */
							bRight = true;
							break;
						case 40:/* 下 */
							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:/* ctrl+1 */
							bCtrlKey && (oBox.style.background = "green");
							break;
						case 50:/* ctrl+2 */
							bCtrlKey && (oBox.style.background = "yellow");
							break;
						case 51:/* ctrl+3 */
							bCtrlKey && (oBox.style.background = "blue");
							break;
					}

					return false
				};

				document.onkeyup = function(event) {
					switch ((event || window.event).keyCode) {
						// 停止按键时,所有事假取消
						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>
posted @ 2022-04-02 09:48  coderwcb  阅读(41)  评论(0)  编辑  收藏  举报