Uncaught InvalidStateError: Failed to set the 'value' property on 'HTMLInputElement': This input element accepts a filename, which may only be programmatically set to the empty string.

使用 HTML5 的图片上传api的时候报如下错误：

Uncaught InvalidStateError: Failed to set the 'value' property on 'HTMLInputElement': This input element accepts a filename, which may only be programmatically set to the empty string.

　出现这个bug的原因是，input元素 blur的时候，需要将上次图片的input元素的value设置为空字符串，就不会报错了。

http://stackoverflow.com/questions/29720794/jquery-select-input-file-and-also-set-it-to-another-input