html的input type=file
文件上传:https://www.zhangxinxu.com/wordpress/2015/11/html-input-type-file/
some与every的使用:https://blog.csdn.net/qq_40190624/article/details/82533610
JavaScript 创建下载文件之Blob和File: https://juejin.cn/post/7031345096062664712
只要思想不滑坡,办法总比困难多!