This example overlays a heatmap on top of the map. It includes buttons that allow users to change the appearance of the heatmap.
Read the documentation.
Git and Node.js are required to run this sample locally. Follow these instructions to install Node.js and NPM. The following commands clone, install dependencies and start the sample application.
git clone -b sample-layer-heatmap https://github.com/googlemaps/js-samples.git
Other samples can be tried by switching to any branch beginning with
git checkout sample-SAMPLE_NAME