Should web client, mobile client and server code be in the same or separate repos?


I’m looking to create an app with meteor that has a web component (made with React) and a mobile component (made with React Native). There is some code I would like to share between the web and mobile app. The “natural” way to do this seems to be to create one repo for the server and react client, and a second repo for the react native app, but it seems really weird to me that the web client should be in the same repo as the server but not the mobile client. Does it make more sense to keep them all in one repo? Or to split them up into separate ones (with a fourth one for shared code?). And for both approaches, how would you organize your folder structure?