The JB-4, developed under project MX-607, was a basically a GB-4 guided glide bomb fitted with a Ford PJ31 pulsejet engine (the same type as used in the JB-2/LTV-N-2) to extend the standoff range to 120 km (75 miles).
Like the GB-4, it was equipped with an AN/AXT-2 TV transmitter, sending its TV camera image to an operator in the launching aircraft, who could send radio commands to change the course of the missile.
The JB-4 is reported as a surface-to-surface missile in some official records, so it seems that is was also intended for ground launch.
The missile was tested in 1945, but the program was cancelled at the end of World War II.