At the beginning, let's see three of this game's captures.
Yes, As what you see in these pictures, you can use javascript language to program in script panel at the bottom of browser. You toggle ALT+Enter to show or hide the panel. You can type Ctrl+Enter to run your program which will help you to product your creeps and command them to do things. If you are confused for some APIs, you can look up the documents which will help you a lot.
The next section will express my feelings when I first met the Screeps.
I found a good game, called screeps. it's game in code. I suddenly realized that this kind of coding style was familiar with what i've learned recently when i learn part one in tutorial. Yes! It's commonJs coding style. After I scanned the catalogue of tutorial, it made me surprised. In part two, I would learn how to upgrading controller. I don't know whether this controller is similar with 'C' in MVC or not. but, who care. I'm excited now. One of the reason is in recent two weeks, I have learned how to use a MV* framework to build my SPA. As I'm a green hand in this field, so I need more interesting ways to inspire me do more practice for enhancing my programmer skills and which will help me understand the concepts of MV* and others. I enjoy it.