leaflet 2.0.0

This is a companion discussion topic for the original entry at https://www.rstudio.com/blog/leaflet-2-0-0

leaflet 2.0.0 is now on CRAN!
The leaflet R package wraps the Leaflet.js JavaScript library, and this release of the R package marks a major upgrade from the outdated Leaflet.js 0.7.x to the current Leaflet.js 1.x (specifically, 1.3.1).
Leaflet.js 1.x includes some non-backward-compatible API changes versus 0.7.x. If you’re using only R code to create your Leaflet maps, these changes should not affect you. If you are using custom JavaScript, some changes may be required to your code.