本地新建个html，复制以下代码，浏览器打开看效果
<!DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="utf-8">
<title>Lightbox</title>
<meta name="description" lang="en" content="Lightbox is a script used to overlay images on the current page. It's a snap to setup and works on all modern browsers."/>
<meta name="author" content="Lokesh Dhakar">
<meta name="viewport" content="width=device-width, initial-scale=1">
<script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
<style type="text/css">
.fillbg { background-color: rgba(0, 0, 0, 0.6); bottom: 0; height: 100%; left: 0; opacity: 0; position: fixed; right: 0; top: 0; width: 100%; z-index: 1100; display:none; }
.fillbg-active { opacity: 1; display:block; }
</style>
</head>
<body>
<img class="comment_pics" style="margin-top:500px;margin-left:500px;" width="50px" height="50px" src="http://www.yyyweb.com/demo/lightbox/img/demopage/image-1.jpg"/>
<div class="bg">
<img class="bgImg" style="max-width: 100%; max-height: 100%; position: fixed;" src="">
</div>
</body>
</html>
<script>
var newImg;
var clientH=$(window).height();
var clientW=$(window).width();
var w = '250';
var h = '250';
$(document).ready(function(){
$(".comment_pics").bind("click", function(){
newImg = $(this)[0].src;
$("body").append('<div class="fillbg"></div>');
$(".fillbg").addClass("fillbg-active");
$('.bgImg').css({'width': w+"px",'height': h+"px",'top':(clientH-h)/2+"px",'left':(clientW-w)/2+"px",'z-index':1101});
$('.bgImg').attr("src",newImg);
});
$(".bgImg").bind("click", function(){
$(".fill-input").removeClass("fill-input-active");
setTimeout(function(){
$(".fillbg-active").removeClass("fillbg-active");
$(".fillbg").remove();
},300);
$('.bgImg').css({'width': '0px','height': '0px'});
$('.bgImg').attr("src",'');
});
});
</script>