Javascript question

Ok, so imagine that I have an HTML image map and I want to have the links clickable only on or after certain dates. (Yep: Advent calendar!) Is there a nice quick easy Javascript way of doing this? My google-fu and /or my brain are not asking the right questions. And I am running out of coding time ...

(Logic basically: IF TODAY > X THEN LINK = Something Useful ELSE LINK = Stay Put)

Edit: I know how to use the date functions in Javascript and I know how to check the current date against a number. What I don't know is how to make the link dependent on the result.

Further edit: no more LJ til late this evening ...