Minimal example using elevation plugin with R leaflet

library(dplyr)
library(jsonlite)
library(leaflet)
library(htmlwidgets)
library(htmltools)

Import gpx track and convert to geojson

source("R/tidy_gpx.R")
## import gpx track
track <- tidy_gpx("data/Move_2017_07_12_11_47_34_Cycling.gpx")
track

## # A tibble: 476 x 4
##         lat      lon      ele                time
##       <dbl>    <dbl>    <dbl>              <dttm>
##  1 60.53521 8.207308 799.0000 2017-07-12 08:47:34
##  2 60.53521 8.207295 799.0000 2017-07-12 08:47:39
##  3 60.53524 8.207430 798.9797 2017-07-12 08:48:38
##  4 60.53528 8.207570 798.6788 2017-07-12 08:48:41
##  5 60.53534 8.208882 794.3352 2017-07-12 08:49:41
##  6 60.53408 8.205974 794.0000 2017-07-12 08:50:41
##  7 60.53406 8.205976 793.9864 2017-07-12 08:50:47
##  8 60.53397 8.206029 792.9795 2017-07-12 08:51:04
##  9 60.53324 8.204063 791.0000 2017-07-12 08:51:42
## 10 60.53199 8.199522 784.0000 2017-07-12 08:52:42
## # ... with 466 more rows

## reorder columns
track <- track %>% select(lon, lat, ele)
## bounding box coordinates
bb <- track %>% summarise_at(vars(lon, lat), funs(min, max))
bb

## # A tibble: 1 x 4
##   lon_min  lat_min  lon_max  lat_max
##     <dbl>    <dbl>    <dbl>    <dbl>
## 1 7.21273 60.49316 8.208882 60.69084

## Convert to json
track <- toJSON(track, dataframe = "values")
geojson <- sprintf('{"type":"Feature","geometry":{"type":"LineString","coordinates":%s},"properties":null}', track)
## unbox magic
geojson <- toJSON(fromJSON(geojson), auto_unbox = TRUE)
# Check if correct geojson objects
geojsonlint::geojson_lint(geojson)

## [1] TRUE

Javascript dependencies

elevationPlugin <- htmlDependency("Leaflet.elevation", "0.0.4",
      src = "js/elevation/",
      script = "leaflet.elevation-0.0.4.src.js",
      stylesheet = "leaflet.elevation-0.0.4.css")
d3Plugin <- htmlDependency("d3", "3.5.17",
      src = "js/d3/",
      script = "d3.js")
registerPlugin <- function(map, plugin) {
  map$dependencies <- c(map$dependencies, list(plugin))
  map
}

Leaflet map

leaflet() %>% 
  fitBounds(bb$lon_min, bb$lat_min, bb$lon_max, bb$lat_max) %>%
  addProviderTiles(providers$Esri.NatGeoWorldMap) %>% 
  # Register plugins on this map instance
  registerPlugin(d3Plugin) %>% 
  registerPlugin(elevationPlugin) %>%
  # Add JS, `this` refers to the Leaflet map.
  onRender('function(el, x, data) {
          var elev = L.control.elevation({width: 300});
              elev.addTo(this);
          L.geoJson(data, {
          onEachFeature: elev.addData.bind(elev)}).addTo(this);
          }', data = geojson)