Static Resources and Visual Force Pages

Note that these are not "resources" in the sense that your salespeople or delivery trucks are "resources." Static Resources are Salesforce records that developers can use to extend the way DayBack behaves.

Alternate DayBack JavaScript

DayBack installs an example static resource named Alternate DayBack JavaScript as a way to show developers that they can upload their own. Developers can use an alternate Static Resource if they wanted to run some custom JavaScript outside of canvas/the iFrame.

DayBack started including this before we introduced App Actions, and many things you'd do with static resources can now be done in actions, but static resources still have a role to play in some customizations. Notably, they're used when embedding DayBack on a record's page to show just the events for a particular account.

DayBack's app actions run inside the DayBack iFrame. But anything that happens at the Salesforce level needs to happen in the JavaScript in the static resource, e.g. navigation, resizing the iFrame, or opening a modal. We have built many of these things (like modals) into the static resource that ships with DayBack, but some developers may want to add their own JS.

There's a pub/sub model here, so that we can publish JS events from DayBack to the VF page and have them run there. It's very much like calling a FM script from DayBack. The "script" that you want to call needs to be set up as a subscription in the static resource. We use a custom static resource sometimes if the customer wants custom navigation, e.g. we replace the static resource's navigation methods so the SF page opens in a new tab, for example.
You can't edit the stock Static Resource that comes with the package, but you can replace it and then enter its name in the custom setting. There is then a simple Apex class that runs when the VF page loads and looks at that custom setting and will load the alternate static resource, instead of the stock one, if specified. If you want to specify URL parameters, then you do this in the static resource as well. Since DayBack is in a special iFrame, you can't specify the parameters in the iFrame URL and need to set them in the static resource and then they're "published" to DayBack and applied. 
Old version of DayBack also didn't have the modal methods set up in the static resource, so back in the day, if you wanted to add those, you would need to follow this path. You can see this in the old instructions in the below blog post, that have since been updated since these methods were added to the stock static resource: That page has a nice description of how these resources actually work.