input[file]標籤的 accept 屬性可用於指定上傳文件的 MIME 類型。
<input type="file" name="file" class="element" accept="image/*">
這段代碼在 Chrome 和 Safar i等 Webkit 瀏覽器下卻出現了響應滯慢的問題，可能要等 6~10s 才能彈出文件選擇對話框。簡直不能忍呀。
在 IE 和 Firefox 中使用 accept="image/" 屬性則沒有發現響應延遲的問題。
於是幾經嘗試後，發現是 accept="image/" 屬性的問題，刪掉它 或者 將 * 通配符 修改爲指定的 MIME 類型，就可以解決 Webkit 瀏覽器下的對話框顯示滯慢的問題。
解決辦法如下：
<input type="file" accept="image/gif,image/jpeg,image/jpg,image/png">
擴展---
後綴名 MIME名稱
*.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 aplication/zip
*.xlsx application/vnd.openxmlformats-officedocument.spreadsheetml.sheet