Download file from R shiny - anjana3/R-Programming- GitHub Wiki
(How to download the single file and multiple files from R shiny)
https://cran.r-project.org/web/packages/periscope/vignettes/downloadFile-module.html
https://cran.r-project.org/web/packages/periscope/vignettes/downloadablePlot-module.html
(How to download the markdown reports from r shiny)
(Detail code for RMD)
https://community.rstudio.com/t/generating-markdown-report-in-shiny/1162/12
(How to integrate the progress bar while we download the file from download button)
https://stackoverflow.com/questions/54277922/loading-message-for-slow-downloadhandler
(How to hide the download button and do observevent)
https://community.rstudio.com/t/how-to-stop-download-in-downloadhandler/8268/2