如何使用JavaScript解码base64编码的文件

My company has a very strict intranet for work related, the net has a single doorway to allow files in and out. The doorway's security does not allow special kinds of files (*.txt, *.doc etc only), and even in those specific kinds of files, it searches for patterns that approve that the file is really that kind. (You can't simply disguise a *.zip file as a *.doc file.)My company has a very strict intranet for work