Upgrade notes for Shiny 1.0.2

This is a hotfix release of Shiny. The primary reason for this release is because the web host for MathJax JavaScript library is scheduled to be shut down in the next few weeks. After it is shut down, Shiny applications that use MathJax will no longer be able to load the MathJax library if they are run with Shiny 1.0.1 and below. (If you don’t know whether your application uses MathJax, it probably does not.) For more information about why the MathJax CDN is shutting down, see https://www.mathjax.org/cdn-shutting-down/.

Full changelog

Minor new features and improvements

Added a shiny:sessioninitialized Javascript event, which is fired at the end of the initialize method of the Session object. This allows us to listen for this event when we want to get the value of things like Shiny.user. (#1568)
Fixed #1649: allow the choices argument in checkboxGroupInput() to be NULL (or c()) to keep backward compatibility with Shiny < 1.0.1. This will result in the same thing as providing choices = character(0). (#1652)
The official URL for accessing MathJax libraries over CDN has been deprecated and will be removed soon. We have switched to a new rstudio.com URL that we will support going forward. (#1664)

Full changelog

Minor new features and improvements

Bug fixes