I have just donwloaded Apache Cordova and it seems like there are platform specific versions. Do I have to code for a specific platform before porting it to another? Is it possi
As long as you don't need the API, you can code everything in your browser. However, when you want to test the Cordova API features, you must run on a platform.
The platform specific files (e.g. the eclipse project for android) contain a www folder (assets/www for android) where you have to put all of your code. Within that folder, everything should be cross-platform, with one exception: the cordova.js file that contains the bridge to the native code for each platform.
You can also try Ripple to run a project directly on your browser, which has the advantage of better debugging tools. It is far from being feature comple though.