Defy Danger

I am new to Roll20 so I have a basic question. When you play Dungeon World and have to do a Defy Danger roll, you first have to choose which attribute to use. Is it possible to create a macro/script that open a quick window enabling the caller to select the attribute and then roll 2D6+ the attribute modifier and return the value?

Yeah, there should be no need for a script.  The dice rolling summary is a very good place for you to start when looking for stuff like this, but briefly, you have a few options.  You could do something like 6 different macros, 1 for each attribute.  Or you could make a macro that's just a part of an expression (e.g. '/roll 2d6+') and fill in the rest with the syntax of choice in the chat box.  Or you could make a macro that's like that, but uses a dice query '?' afterwards to ask which attribute you want to use in a popup window.  So there're a few options, depending upon how quick you want it to work.  6 macros is fastest to use, probably, while the latter two would depend upon your typing vs. mousing speed.

Can a set of 6 macro work or should each set be tailored to a specific character? When I try to use the auto-complete after the @ it only gives me the Attribute from a specific charater (Ashol Enaran): /roll 2d6+@{Ashol Enaran|CONstitution}  Is it possible to replace Ashol Enaran by the macro caller?

The Dungeon Master said: Can a set of 6 macro work or should each set be tailored to a specific character? When I try to use the auto-complete after the @ it only gives me the Attribute from a specific charater (Ashol Enaran): /roll 2d6+@{Ashol Enaran|CONstitution}  Is it possible to replace Ashol Enaran by the macro caller? No, but if Ashol Enaran's player is the only one who can see the macro that looks at Ashol's CON, it doesn't really matter, does it? ;) If Ashol Enaran's player makes the macro, the other players don't see it. If the GM makes the macro, you can set it so that only Ashol's player sees it.