Best way to include a large algorithm

I am trying to convert a game from Gamemaker to Construct2 and I have one very large algorithm (about 600 lines) that sets up each level of the game. I probably could translate this into an event but I could see this as difficult to write and more difficult to maintain.

Is there anyway to have this become an importable Javascript function?

That's pretty vague.

But, then again so is saying to take a look at the plugin sdk.

https://www.scirra.com/manual/15/sdk