How to get access to the elements of the Array?

i got one question. I got a couple of links stored in an Array called A. Now i am using d3 and i want to change the stroke-width of all the link-elements that are stored in the array A. How can i fill my if condition in the right way to do this? I thought about include, but not sure which is the right way.

link.style("stroke-width", function(d) 
                {
                  if(....)

                });