// Grant CesiumJS access to your ion assets
Cesium.Ion.defaultAccessToken = "XXX";

try {
  const viewer = new Cesium.Viewer("cesiumContainer", {
    terrainProvider:
      await Cesium.CesiumTerrainProvider.fromIonAssetId(1),
  });

  var handler = new Cesium.ScreenSpaceEventHandler(viewer.canvas);
  handler.setInputAction(async function(event) {
      var position = viewer.scene.pickPosition(event.position);
      if (Cesium.defined(position)) {
          var carto = Cesium.Cartographic.fromCartesian(position);
          var lat = Cesium.Math.toDegrees(carto.latitude);
          var lon = Cesium.Math.toDegrees(carto.longitude);

          console.log("Getting sample...");
          try {
              // Using async/await to handle the promise returned by sampleTerrainMostDetailed
              var updatedPositions = await Cesium.sampleTerrainMostDetailed(viewer.terrainProvider, [carto]);
              console.log("Lon: " + lon + "\nLat: " + lat + "\nHeight: " + updatedPositions[0].height);
          } catch (error) {
              console.error("Error sampling terrain: ", error);
          }
      }
  }, Cesium.ScreenSpaceEventType.LEFT_CLICK);

} catch (error) {
  console.log(error);
}