Passing variables between functions

Hi, is there a way to pass variables between functions? The way I've been handling data is via the HTML header but would ideally like to keep sensitive data within a function.

a typical Hypefunction has three Arguments: hypeDocument, element and event. if you want to pass additional data you can simply add more arguments ...


Thank you so much, guess I just needed a push to explore a bit more. Managed to utilise the hypeDocument.customData function.