Leaflet is a widely used open source JavaScript library used to build web mapping applications
library(leaflet)
library(maps)
You can also embed plots, for example:
Below you will see the maps layaut of the birthplace of R:
m <- leaflet() %>%
addTiles() %>% # Add default OpenStreetMap map tiles
addMarkers(lng=174.768, lat=-36.852, popup="The birthplace of R")
m