How do I grab a keyboard event while focused on a text input ?

The tittle says it all.

I wrote an event that has to react when pressing the UP / DOWN arrows but they won't work while a text input is focused.

That's so un-ergonomic to have to click anywhere else to unfocus, then press the UP / DOWN arrows until you have what you want and focus back on the text input.

Is there anyways to make it works without unfocusing ?