input:file上傳文件類型（超詳細）
imput 屬性有以下幾種：
1.type:input類型這就不多說了
2.accept：表示可以選擇的文件類型，多個類型用英文逗號分開，常用的類型見下表。
<input id="file" type="file" accept="image/png,image/gif" name="file" /> - 1
3.multiple：是否可以選擇多個文件，多個文件時其value值為第一個文件的虛擬路徑。
<input id="files" type="file" multiple="multiple" name="file"
下面就是各種文件類型（上傳給接口時）
*.3gpp audio/3gpp, video/3gpp *.ac3 audio/ac3 *.asf allpication/vnd.ms-asf *.au audio/basic *.css text/css *.csv text/csv *.doc application/msword *.dot application/msword *.dtd application/xml-dtd *.dwg image/vnd.dwg *.dxf image/vnd.dxf *.gif image/gif *.htm text/html *.html text/html *.jp2 image/jp2 *.jpe image/jpeg *.jpeg image/jpeg *.jpg image/jpeg *.js text/javascript, application/javascript *.json application/json *.mp2 audio/mpeg, video/mpeg *.mp3 audio/mpeg *.mp4 audio/mp4, video/mp4 *.mpeg video/mpeg *.mpg video/mpeg *.mpp application/vnd.ms-project *.ogg application/ogg, audio/ogg *.pdf application/pdf *.png image/png *.pot application/vnd.ms-powerpoint *.pps application/vnd.ms-powerpoint *.ppt application/vnd.ms-powerpoint *.rtf application/rtf, text/rtf *.svf image/vnd.svf *.tif image/tiff *.tiff image/tiff *.txt text/plain *.wdb application/vnd.ms-works *.wps application/vnd.ms-works *.xhtml application/xhtml+xml *.xlc application/vnd.ms-excel *.xlm application/vnd.ms-excel *.xls application/vnd.ms-excel *.xlt application/vnd.ms-excel *.xlw application/vnd.ms-excel *.xml text/xml, application/xml *.zip application/zip *.xlsx application/vnd.openxmlformats-officedocument.spreadsheetml.sheet