图片轮播，实现当前图片的前一张，后一张

[一只红烧虾]

我写了js，我想要的效果是，几张图片轮播，按向左的按钮就换到当前图片的上一张，按向右的按钮就换到，当前图片的下一张，但是我现在实现的效果是，第一次按向前的按钮就换到了数组中的第一张，第二次按就是数组中第二张，请问怎样修改才能实现我想要的效果？ <script type="text/javascript"> window.onload = function() { setInterval('ChangeImg()',1500); } var i = 1; function ChangeImg(){ i += 1; document.getElementById('img').src = 'image/img'+ i +'.jpg'; if(i==7){ i=0; } } </script> <script type="text/javascript"> var imgArr = ["image/img1.jpg","image/img2.jpg", "image/img3.jpg","image/img4.jpg","image/img5.jpg", ,"image/img6.jpg","image/img7.jpg"]; var index = 0; function next(){ document.getElementById('img').src=imgArr[index]; index++; if(index==imgArr.length){ index=0; } } function back(){ document.getElementById('img').src = imgArr[index]; index --; if(index<0){ index=imgArr.length-1; } } </script>

[似水流年风萧兮]

<script type="text/javascript">
		var imgArr = ["image/img1.jpg", "image/img2.jpg", "image/img3.jpg", "image/img4.jpg", "image/img5.jpg", "image/img6.jpg", "image/img7.jpg"];
		var index = 0;
		function next() {
			index++;
			if (index == imgArr.length) {
				index = 0;
			}
			document.getElementById('img').src = imgArr[index];
		}
		function back() {
			index--;
			if (index < 0) {
				index = imgArr.length - 1;
			}
			document.getElementById('img').src = imgArr[index];
		}
	</script>

document.getElementById('img').src = imgArr[index];你要放在变化后的索引后面。而且你定义的数组有问题，没看到两个逗号连在一起吗

[南宫廿贰]

用前端框架。