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）

逃离我推掉我的手 2021-11-09 11:48 259阅读 0赞

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDc5NzE4Mg_size_16_color_FFFFFF_t_70]

<!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>

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDc5NzE4Mg_size_16_color_FFFFFF_t_70]: /images/20211109/c29441800b19475596551c05a6dcd69e.png