We will use "CustomJavascript" to add our own Javascript.
The CustomJavascript handles events and modifies the map after events.
That is to say, with the CustomJavascript we will add the Javascript that will be executed (for example) to respond to a button click.
However, the Javascript added will never be executed when loading the map itself: for that we have
CustomInsideJavascript
To use CustomJavascript, we will have to use the method "ToString()" to output elements of our control in Javascript for the Google API. For example, the GMarker.
We can see it better in the example. In this example, we can add icons to the center of the map, erase the last icon added, or erase all the icons that are there.