String to object variable

I’m trying to format a variable into the middle of an object so that I can pass the entire thing as a parameter to a javascript function via ExternalInterface, but I cannot figure out how to format the data correctly.

I need it to end up looking like this:

{gallery:'myvar'}

braces and apostrophes included. myvar would be my variable data, which is a string. I tried connecting it all together as a big string, but the javascript function didnt like that. It did accept it if I typed the entire thing staticly as an object variable and passed that. Is there any way I can format it all into a string and then convert the string data to an object? or is there another way to try and accomplish something like this? thanks