<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<title>PreLoading</title>
<style>
*{margin:0; padding:0; border:none; outline:0; text-decoration:none;}
html,body,.box{width:100%; height:100%;}
.box{display:none;}
#img{width:90%; height:90%; margin:2vh auto 0; display:block; box-shadow:0 0 10px gray;}
.box .btns{width:140px; height:40px; display:block; margin:20px auto;}
.box .btns .btn{width:60px; height:40px; display:block; border:1px gray solid; background-color:#ccc; text-align:center; line-height:40px; float:left;}
.box .btns .btn:nth-of-type(2){margin-left:16px;}
.load{width:100%; height:100%; display:block; font-size:60px; font-family:"微软雅黑"; color:#ccc; text-align:center; line-height:100vh; position:fixed;}
</style>
</head>
<body>
<div class="box">
<img id="img" src="" alt="pic">
<p class="btns"><a href="javascript:" class="btn">prev</a><a href="javascript:" class="btn">next</a></p>
</div>
<p class="load">0%</p>
<script type="text/javascript">
var imgs = ['http://down.699pic.com/photo/50036/7661.jpg?_upt=da51378d1494571758&_upd=500367661.jpg',
'http://desk.fd.zol-img.com.cn/t_s1920x1080c5/g5/M00/09/0F/ChMkJljskIqIPX9bAAMPyuIn8DcAAbj8QB7XpYAAw_i343.jpg',
'http://desk.fd.zol-img.com.cn/t_s1920x1080c5/g5/M00/09/0F/ChMkJljskLeIaW-JAAIudN_yqvgAAbj8gDQO5AAAi6M64.jpeg',
'http://desk.fd.zol-img.com.cn/t_s1920x1080c5/g5/M00/0F/08/ChMkJlauzISIH0uXAARUHuJLVX8AAH8-gHu6zsABFQ2166.jpg',
'http://desk.fd.zol-img.com.cn/t_s1920x1080c5/g5/M00/0F/08/ChMkJlauzISIIL5TAAObxg4-XeUAAH8-gHzP3EAA5ve000.jpg'];
// 绑定按钮事件
var btns = document.getElementsByClassName('btn'),
img = document.getElementById('img'),
index = 0;
for(var i=0;i<btns.length;i++){
btns[i].onclick = function(){
if(this.innerHTML === 'next'){
index = Math.min(++index , imgs.length-1);
img.setAttribute('src',imgs[index]);
}
if(this.innerHTML === 'prev'){
index = Math.max(--index , 0);
img.setAttribute('src',imgs[index]);
}
}
}
// 计数变量
var count = 0,
load = document.getElementsByClassName('load')[0],
box = document.getElementsByClassName('box')[0];
// 有序预加载
var imgObj = new Image();
function loading(){
imgObj.onload = function(){
load.innerHTML = Math.round((count + 1) / imgs.length * 100) + '%';
if(count >= imgs.length){
load.style.display = 'none';
box.style.display = 'block';
img.setAttribute('src',imgs[0]);
document.title = '1/' + imgs.length;
}
else{
loading();
}
}
imgObj.onerror = function(){
load.innerHTML = Math.round((count + 1) / imgs.length * 100) + '%';
if(count >= imgs.length){
load.style.display = 'none';
box.style.display = 'block';
img.setAttribute('src',imgs[0]);
document.title = '1/' + imgs.length;
}
else{
loading();
}
}
imgObj.src = imgs[count];
count++;
}
loading();
</script>
</body>
</html>
