/图片无序预加载
(function($){
function Preload(imgs,fns){
this.imgs=(typeof imgs==="string")?[imgs]:imgs;
this.fns=$.extend({},Preload.fns,fns);//把fns 覆盖到Preload上 然后添加到{}返回
if(this.fns.loadMethod=="unorderload"){//是无序 还是有序
this._unorderload();
}
else{
this._orderload();
}
}
Preload.fns={
loadMethod:null,//有序还是无序的方式
eachLoadImg:null, //每张图片加载完所执行的函数
allLoadImg:null //所有图片加载完所要执行的函数
}
Preload.prototype._orderload=function(){
var imgs=this.imgs,
len=imgs.length,
fns=this.fns,
num=0;
function load(){
var imgObj=new Image();
$(imgObj).on("load error",function(){
fns.each && fns.each(); //存在 才会执行
if(num<len){
load(); //没有加载完就继续加载 函数执行是有顺序的
}
else{
fns.allLoadImg && fns.allLoadImg();//加载完全部
}
});
imgObj.src=imgs[num];
num++;
}
load();
}
Preload.prototype._unorderload=function(){
var imgs=this.imgs,
len=imgs.length,
fns=this.fns,
num=0;
$.each(imgs,function(i,src){
if(typeof src!="string") return;
var imgObj=new Image();
$(imgObj).on("load error",function(){
fns.eachLoadImg && fns.eachLoadImg(num,len);
if( num==len-1){
fns.allLoadImg && fns.allLoadImg();
}
num++;
});
imgObj.src=src;
});
}
$.extend({ //给jQuery上增加新函数
preload:function(imgs,fns){
new Preload(imgs,fns);
}
});
})(jQuery);使用方法
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<meta name="Generator" content="EditPlus?">
<meta name="Author" content="">
<meta name="Keywords" content="">
<meta name="Description" content="">
<title>有序预加载</title>
<style>
*{margin: 0; padding: 0;}
img{
width:100%;
vertical-align:top;
}
.imgBox{
width:500px;
margin:100px auto;
}
#prevImg, #nextImg{
width:60px;
font-size:15px;
height:30px;
line-height:30px;
text-align:center;
background: #686868;
position:absolute;
color:#000;
text-decoration:none;
margin-top:-50px;
}
#prevImg{
left:40%;
}
#nextImg{
left:55%;
}
</style>
<script src="js/jquery-3.2.1.js"></script>
<script src="js/unorderload.js"></script>
<script>
$(function(){
var imgs=["img/0.jpg","img/1.jpg","img/2.jpg","img/3.jpg","img/4.jpg","img/5.jpg","img/6.jpg","img/7.jpg"];
var len=imgs.length;
var index=0;
$.preload(imgs,{});
$("#control-img-btn").on("click","a",function(){
if($(this).hasClass("prevImg")){
index=Math.max(0,--index); //上一张
}
else{
index=Math.min(len-1,++index);//下一张
}
$("#imgBox img").attr("src",imgs[index]);
});
});
</script>
</head>
<body>
<div id="imgBox">
<img />
</div>
<p id="control-img-btn">
<a href="javascript:;" id="prevImg">上一页</a>
<a href="javascript:;" id="nextImg">下一页</a>
</p>
</body>
</html>