learnJavaScript/lesson1.1.html at master · zzcypc/learnJavaScript · GitHub

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<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			#square {
				height: 100px;
				width: 100px;
				margin: 10px auto 0 auto;
				background-color: greenyellow;
			}

			#control {
				text-align: center;
			}
		</style>
	</head>

	<body>
		<div id="control">
			<button>变宽</button>
			<button>变高</button>
			<button>变色</button>
			<button>隐藏</button>
			<button>显示</button>
		</div>
		<div id="square"></div>
	</body>
	<script>
		var changeStyle=function(elem,arr,value){
			elem.style[arr]=value;
		};
		var oBtn=document.getElementById("control").getElementsByTagName("button");
		var oDiv=document.getElementById("square");
		var oArr=["width","height","background","display","display"];
		var oVal=["200px","200px","red","none","block"];

		window.onload=function(){
			for(var i=0;i<=oBtn.length;i++){
				oBtn[i].index=i;//此处有疑问
				oBtn[i].onclick=function(){
					changeStyle(oDiv,oArr[this.index],oVal[this.index]);
				}
			}
		};
	</script>

</html>