I am developing an app to android and ios, which purpose is get directions to a certain clicked marker (point) in the map.
So, I am using the Google Maps API with node.js, and I have the data from the points stored in a MongoDB.
I've been serching but I can't find anything that solves what I want to do.

I want now to get those points coordinates from the data base object and then use the coordinates to when I click a marker (a point), then appears a infowindow with a button saying "go to location" and when I click this button I will have the directions from the point where I am(or where any other user is like, a current location) to the clicked marker. I don't know if I explained myself clearly, but let me know.

If you could help, that would be great, I am in a bit of a hurry with this because I have a deadline and I am a little bit new to Node.js.