Hello, frends. In my aplication Window size 800x480, in CocoonJS set Application Scale Method - scale to fit. What are the problems with scaling can arise in such settings on the iPhone 4 and 5, as well as on the screens of 1280x720 and 1920x1080?
Develop games in your browser. Powerful, performant & highly capable.
You should read the following tutorial
And you also need to test on multiple devices. There is no short cuts to avoid testing.