为什么Nginx下的gzip不压缩javascript了

因为Nginx下的gzip默认不压缩javascript、图片等静态资源文件
可以通过gzip_types指定需要压缩的MIME类型
gzip on;
gzip_types text/plain application/x-javascript text/css text/javascript;
MIME(Multipurpose Internet Mail Extensions)多用途互联网邮件扩展类型。是设定某种扩展名的文件用一种应用程序来打开的方式类型，当该扩展名文件被访问的时候，浏览器会自动使用指定应用程序来打开。多用于指定一些客户端自定义的文件名，以及一些媒体文件打开方式。
常见MIME类型参考：
格式前面为后辍名，后面为对应的MIME型（例如：rar application/x-rar-compressed 表示。RAR对应的是application/x-rar-compressed ）
{ ".apk", "application/vnd.android.package-archive" },
{ ".asp", "application/x-asap" },
{ ".flv", "flv-application/octet-stream" },
{ ".gif", "image/gif" },
{ ".gz", "application/x-gzip" },
{ ".htc", "text/x-component" },
{ ".htm", "text/html" },
{ ".html", "text/html" },
{ ".ico", "image/x-icon" },
{ ".jpeg", "image/jpeg" },
{ ".jpg", "image/jpeg" },
{ ".js", "application/x-javascript" },
{ ".mht", "message/rfc822" },
{ ".mhtml", "message/rfc822" },
{ ".mp3", "audio/mpeg" },
{ ".mp4", "video/mp4" },
{ ".mpa", "video/mpeg" },
{ ".mpeg", "video/mpeg" },
{ ".mpg", "video/mpeg" },
{ ".mpg4", "video/mp4" },
{ ".pdf", "application/pdf" },
{ ".png", "image/png" },
{ ".ppt", "application/vnd.ms-powerpoint" },
{ ".pptx", "application/vnd.openxmlformats-officedocument.presentationml.presentation" },
{ ".pqf", "application/x-cprplayer" },
{ ".rf", "image/vnd.rn-realflash" },
{ ".rgb", "image/x-rgb" },
{ ".rmvb", "audio/x-pn-realaudio" },
{ ".shtml", "magnus-internal/parsed-html" },
{ ".swf", "application/x-shockwave-flash" },
{ ".tif", "image/tiff" },
{ ".wml", "text/vnd.wap.wml" },
{ ".xhtm", "application/xhtml+xml" },
{ ".xhtml", "application/xhtml+xml" },
{ ".xla", "application/vnd.ms-excel" },
{ ".xlc", "application/vnd.ms-excel" },
{ ".xll", "application/x-excel" },
{ ".xlm", "application/vnd.ms-excel" },
{ ".xls", "application/vnd.ms-excel" },
{ ".xlsx", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" },
{ ".xlt", "application/vnd.ms-excel" },
{ ".xlw", "application/vnd.ms-excel" },
{ ".xm", "audio/x-mod" },
{".xml","text/plain"},
{".xml","application/xml"},[1]
{ ".zip", "application/zip" },
{ ".json", "application/json" },