prolo_mapbox.js.erb

  function loadMapboxGl() {
    /**
     * Load MapBox Assets
     * we either need to load mapbox with requirejs if our customer is using it
     * or we need to load it ourselves.
     *
     * If we wait write out a script tag that loads it well...HERE BE DRAGONS.
     * requirejs could load before mapbox. In this case mapbox will not work and requirejs will not load it.  This is the worst case.
     * At times this will load mapbox even when requirejs will exist later,
     * but this should work since it should be loaded before requirejs.
     *
     */
    /**
     * To update mapbox-gl, update both the requirejs url, the css and the file app/views/embed/mapbox-gl.js.
     */
    if ('mapboxgl' in window) {
      return;
    }
    if ('requirejs' in window) { // if requirejs is loaded before prolo.js.
      requirejs(['https://api.mapbox.com/mapbox-gl-js/v1.10.1/mapbox-gl.js'], function(mapboxgl) {
        window.mapboxgl = mapboxgl;
        if ('ProloInitialization' in window) {
          ProloInitialization();
        }
      });
    } else {
      <%=raw File.read(Rails.root.join('app/views/embed/mapbox-gl.js')) %>
    }
  }