[javascript]Three parts of javascript code snippet

<script>
(function(){
/*
if (navigator.userAgent.toLowerCase().indexOf("iphone") == -1){
$("#id_download_btn img").attr("src" , "http://cache.hinabian.com/mobile/images/downLoadLink.png");
return;
}
*/var oldurl = "http://a.app.qq.com/o/simple.jsp?pkgname=com.hinabian.migrate";
var newurl = "http://m.hinabian.com/dlapp.html";
if (navigator.userAgent.toLowerCase().indexOf("micromessenger") == -1)
{
$("#id_download_btn").click(function(){
location.href = newurl;
});
}else{$("#id_download_btn").click(function(){
location.href = newurl;
});
/*
$("#id_share_info").click(function(){
$(this).hide();
});
*/
}})();</script>
<script>
(function(){
if (navigator.userAgent.indexOf("MicroMessenger") == -1)
return;
var json_config = JSON.parse(window.SIGNPACKAGE);
wx.config({
debug: false ,
appId: json_config.appId ,
timestamp: json_config.timestamp,
nonceStr: json_config.nonceStr,
signature: json_config.signature ,
jsApiList: ['onMenuShareTimeline' , 'onMenuShareAppMessage']
});var title = "";
var desc = "";
var imgUrl = "http://cache.hinabian.com/images/share/logo.jpg";
var shareLink = location.href;
wx.ready(function(){
// 分享到朋友圈
wx.onMenuShareTimeline({
title: '海那边APP，带你了解海外生活，开启你的海外生活！',
link:shareLink,
imgUrl: imgUrl
});
// 分享给朋友
wx.onMenuShareAppMessage({
title: '了解海外生活，下载海那边APP' , // 分享标题
desc: '每年几十万华人去到国外，他们在海外生活怎么样？海那边带你了解海外生活，开启你的海外生活！' , // 分享描述
link: shareLink, // 分享链接
imgUrl: imgUrl, // 分享图标
type: '', // 分享类型,music、video或link，不填默认为link
dataUrl: '' // 如果type是music或video，则要提供数据链接，默认为空
});
});
})();
</script>
<!--统计代码 -->
<script>
var _hmt = _hmt || [];
(function() {
var hm = document.createElement("script");
hm.src = "//hm.baidu.com/hm.js?41c4562713e00298de3d6b8c5a8192ae";
var s = document.getElementsByTagName("script")[0];
s.parentNode.insertBefore(hm, s);
})();
</script>
<script type="text/javascript">
$(window).on("orientationchange" , function(){
$("body").removeClass('redraw');
$("body").addClass('redraw');
});
</script>