favicon支持的图片格式

为网站设置favicon有两种方式：

1、网站根目录下放置名为favicon.ico的图片，浏览器就会自动获取；

2、在页面中通过<link rel="shortcut icon"  href="http://example.com/myicon.ico" />.

对于favicon来说，一般都是使用ico格式，不过对于根目录的favicon图片chrome、firefox、IE11等现代浏览器都支持PNG、GIF（无动画）格式。对于通过link来设置的favicon格式，IE7+、现代浏览器都支持PNG、GIF格式，不过在IE7下图片效果会很差。

对于苹果设备，我们可以通过在head里写入<link rel="apple-touch-icon" href="somepath/image.png" />、<link rel="apple-touch-icon-precomposed" href="somepath/image.png" />来设置。

	Google Chrome	Internet Explorer	Firefox	Opera	Safari
<link rel="shortcut icon" href="http://example.com/myicon.ico" />	Yes[4]	Yes[4][19]	Yes[4]	Yes[4]	Yes
<link rel="icon" href="http://example.com/image.ico" />	Yes	Yes (from IE 11)[20]	Yes	Yes	Yes
<link rel="icon" type="image/vnd.microsoft.icon" href="http://example.com/image.ico" />	Yes	Yes (from IE 9)[20]	Yes	Yes	Yes
<link rel="icon" type="image/png" href="http://example.com/image.png" />	Yes	Yes (from IE 11)[20]	Yes	Yes	Yes
<link rel="icon" type="image/gif" href="http://example.com/image.gif" />	Yes	Yes (from IE 11)[20]	Yes	Yes	Yes
<link rel="icon" type="image/x-icon" href="http://example.com/image.ico"/>	Yes[4]	Yes (from IE 9)[26]	Yes[4]	Yes[4]	Yes
favicon.ico located in the website's root	Yes	Yes	Optional[27]	Optional[28]	Yes
precedence: prefer root or (X)HTML linked version	linked[22]	linked[22]	linked[22]	?	?

参考文档：

http://en.wikipedia.org/wiki/Favicon

http://msdn.microsoft.com/en-us/library/ms537656(v=vs.85).aspx

http://stackoverflow.com/questions/1344122/favicon-png-vs-favicon-ico-why-should-i-use-pngs-instead-of-icos

http://www.webmasterworld.com/html/3701134.htm

http://blogs.msdn.com/b/ieinternals/archive/2013/09/08/internet-explorer-favicons-png-link-rel-icon-caching.aspx

http://blogs.msdn.com/b/jeffdav/archive/2007/03/01/why-doesn-t-the-favicon-for-my-site-appear-in-ie7.aspx