That is javascript for you. In fact, `window` is the global variable context, so `window.STATIC_URL` and `STATIC_URL` are the same. I got into the convention of my colleague front-enders to assign global variables in `window` so that it doesn't like you forgot to add the `var` declaration (that would make it a local variable).

I didn't add `window.` here because it makes the code look a bit cumbersome, but we could if you think it's clearer.