Javascript for any one of multiple fields to set a flag/variable

I need help creating a script that will read through several fields, and if any one of them meets a condition (let's say, "Yes"), then Checkbox1 is checked.

The pseudocode would be:

If Field1 is Yes

     or If Field2 is Yes

     or If Field3 is Yes

     or If Field4 is Yes

then Checkbox1 = checked

So, a "Yes" one of those fields generates the check in the box.

The other part of this is if someone were to set Fields 1-4 to "Yes" and then back to "No",  I need a script that checks all four fields and if they are all "No", then sets Checkbox1 to unchecked.

I can't code, but I know how to edit/add existing script.  I really appreciate any help.