.j.jd (x;d)

Where

returns the result of .j.j unless d`null0w, in which case 0w and -0w are mapped to "null". (Since V3.6 2018.12.06.)

q).j.j -0w 0 1 2 3 0w
"[-inf,0,1,2,3,inf]"
q).j.jd(-0w 0 1 2 3 0w;()!())
"[-inf,0,1,2,3,inf]"
q).j.jd(-0w 0 1 2 3 0w;(!). 1#'`null0w,1b)
"[null,0,1,2,3,null]"