I could possibly get you an example of both if you were interested. Most of the people using Phaser are using Tyepscript and doing multi-module management with that. I use Browserify (and bring in Phaser separately).

If you have a state that loads levels, you change the level targets and restart the state so that the preload runs again and gets the new resources. Or you can load everything up front and approach multiple levels that way.

yes please teach me!

Here is a multi-module project I wrote back in January: https://github.com/georgefrick/PhaserJsDemoGame

Here's a game with multiple levels and multiple .js files I made last June.

Source: https://github.com/frontfish/blobber Play: http://frontfish.net/games/blobber

> 1) examples of phaser games using multiple .js files?

Not a example but you can use Yeoman to organise your code.

https://github.com/codevinsky/generator-phaser-official