input file类型，文件类型的限制

直接限制input type='file'的文件类型限制，通过accept属性进行设定,多个类型用逗号分隔开,因为accept是html5的新特性，所以火狐和IE的支持就显得单薄了，

如:

accept可以指定如下信息：

 

 *.3gppaudio/3gpp, video/3gpp3GPP Audio/Video*.ac3audio/ac3AC3 Audio*.asfallpication/vnd.ms-asfAdvanced Streaming Format*.auaudio/basicAU Audio*.csstext/cssCascading Style Sheets*.csvtext/csvComma Separated Values*.docapplication/mswordMS Word Document*.dotapplication/mswordMS Word Template*.dtdapplication/xml-dtdDocument Type Definition*.dwgimage/vnd.dwgAutoCAD Drawing Database*.dxfimage/vnd.dxfAutoCAD Drawing Interchange Format*.gifimage/gifGraphic Interchange Format*.htmtext/htmlHyperText Markup Language*.htmltext/htmlHyperText Markup Language*.jp2image/jp2JPEG-2000*.jpeimage/jpegJPEG*.jpegimage/jpegJPEG*.jpgimage/jpegJPEG*.jstext/javascript, application/javascriptJavaScript*.jsonapplication/jsonJavaScript Object Notation*.mp2audio/mpeg, video/mpegMPEG Audio/Video Stream, Layer II*.mp3audio/mpegMPEG Audio Stream, Layer III*.mp4audio/mp4, video/mp4MPEG-4 Audio/Video*.mpegvideo/mpegMPEG Video Stream, Layer II*.mpgvideo/mpegMPEG Video Stream, Layer II*.mppapplication/vnd.ms-projectMS Project Project*.oggapplication/ogg, audio/oggOgg Vorbis*.pdfapplication/pdfPortable Document Format*.pngimage/pngPortable Network Graphics*.potapplication/vnd.ms-powerpointMS PowerPoint Template*.ppsapplication/vnd.ms-powerpointMS PowerPoint Slideshow*.pptapplication/vnd.ms-powerpointMS PowerPoint Presentation*.rtfapplication/rtf, text/rtfRich Text Format*.svfimage/vnd.svfSimple Vector Format*.tifimage/tiffTagged Image Format File*.tiffimage/tiffTagged Image Format File*.txttext/plainPlain Text*.wdbapplication/vnd.ms-worksMS Works Database*.wpsapplication/vnd.ms-worksWorks Text Document*.xhtmlapplication/xhtml+xmlExtensible HyperText Markup Language*.xlcapplication/vnd.ms-excelMS Excel Chart*.xlmapplication/vnd.ms-excelMS Excel Macro*.xlsapplication/vnd.ms-excelMS Excel Spreadsheet*.xltapplication/vnd.ms-excelMS Excel Template*.xlwapplication/vnd.ms-excelMS Excel Workspace*.xmltext/xml, application/xmlExtensible Markup Language*.zipaplication/zipCompressed Archive