https://stackoverflow.com/questions/21044798/how-to-use-formdata-for-ajax-file-upload
https://www.jianshu.com/p/a40bc4207c37
https://github.com/SyMind/image-upload
https://isudox.com/2016/04/18/imitate-wechat-moment-on-mobile-device/
插件：
https://www.jq22.com/jquery-info22747
https://www.jq22.com/jquery-info13194
https://www.jq22.com/jquery-info22472
vue图片裁剪(原创)
https://www.jq22.com/jquery-info23097
jQuery图片裁剪插件jQuery-photoClip
https://www.jq22.com/jquery-info7428
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