附上一個demo自定義預加載當前圖后幾張，有興趣的可以把玩一下，請指教

<!DOCTYPE?html>
<html>
<head>
	<title>圖片無序預加載-優(yōu)化</title>
	<meta?charset="utf-8">
	<meta?name="viewport"?content="width=device-width,initial-scale=1.0">
	<meta?name="keywords"?content="your?keywords">
	<meta?name="description"?content="your?description">
	<style>
		*{margin:?0;padding:?0}
		#box{width:?1024px;height:?500px;margin:?50px?auto;}
		img{width:?1024px;height:?450px;border:?1px?solid?red;}
		#click{text-align:?center;}
	</style>
</head>
<body>
	<div?id="box">
		<img?src=""?alt="">
		<div?id="click">
			<a?href=""?id="prev">上一頁</a>
			<a?href=""?id="next">下一頁</a>
		</div>
	</div>
	<script?src="../../js/jquery-3.2.0.js"></script>
	<script>
		var?imgs?=?[
		'https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=4116894745,1605052943&fm=26&gp=0.jpg',
		'https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=644449983,791694252&fm=26&gp=0.jpg',
		'https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=3225666097,3247550499&fm=26&gp=0.jpg',
		'https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=3014020588,2537118876&fm=26&gp=0.jpg',
		'https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=2171490910,189745274&fm=26&gp=0.jpg',
		'https://coding.net/u/ready-/p/study/git/raw/master/img/Magnifier.png',
		'https://coding.net/u/ready-/p/study/git/raw/master/img/Magnifier.png'
		];
		var?index?=?0,
			curImg?=?0,
			num?=?1,//預加載當前圖片后num張圖片..
			len?=?imgs.length;
		$(function?()?{
			$('img').attr('src',imgs[0]);
			$('a').on('click',function(){
				curindex?=?(this.id?===?'prev')???Math.max(0,--index)?:?Math.min(imgs.length-1,++index);
				$('img').attr('src',imgs[curindex]);
				load();
				return?false;
			})
		})
		function?load(){
			var?imgObj?=?new?Image();
			$(imgObj).on('load?error',function(){
				/*if(curImg?>=?len){

				}else{
					load();
				}*/
				if(curImg?<=?index+num){
					load();
					curImg++;
				}
			})
			imgObj.src?=?imgs[curImg];
		}
		load();
	</script>
</body>
</html>