The problem is that when this is `require`d from the mocha test, `exports` exists but `window` doesn't. So `_ = window?._ ?= debounceR: ->` ends up leaving `_` undefined. This was the simplest construct I could think of that worked in both browser and mocha tests.

To be clear, all these lines are an ugly hack that I'm hoping will go away with the larger switch to require.js or whatever