The result also means that relegation-threatened Rotherham, who remain 21st, are out of the bottom three only on goal difference
They had previously a game in hand on 22nd-placed Bristol City.
Cauley Woodrow had required only six minutes to score the first goal under Jokanovic, who was appointed on Sunday and watched Tuesday's action from the stands, and although Farrend Rawson equalised for the visitors in the 20th minute, Woodrow's second restored Fulham's advantage just before half-time.
Alexander Kacaniklic added a third in the 58th minute, before Ross McCormack ended any prospect of a Rotherham comeback 10 minutes later by scoring Fulham's fourth.
A late equaliser from Tom Ince earned Derby a 2-2 draw at Leeds and strengthened the Rams' grip on second place.
Jeff Hendrick had put the visitors in front in only the 13th minute, and although Sol Bamba equalised shortly before half-time, and Chris Wood headed Leeds in front with 20 minutes remaining, Ince scored a 78th-minute leveller to rescue a point.
Derby trail league leaders Middlesbrough by only a point, having played an additional game, and are four ahead of third-placed Hull
Leeds climb above Reading, into 12th.
Ipswich strengthened their pursuit of a play-off place with an impressive 1-0 win at fellow promotion contenders Brighton.
Brighton began the evening hoping victory would take them above Derby and into second place, but Daryl Murphy secured a surprise victory with the game's only goal in the 32nd minute.
The result takes sixth-placed Ipswich within four points of joint-third-placed Hull and Brighton, who both have 44 points, and moves them four ahead of Sheffield Wednesday, who remain seventh.
Cardiff also hope to reach the play-offs, but they dropped two valuable points in a 1-1 home draw with Nottingham Forest.
Oliver Burke's classy finish gave Forest the lead in only the ninth minute, but Aron Gunnarsson's deflected shot, just four minutes later, brought Cardiff level.
Cardiff, in 10th, trail the play-offs by six points
Forest are 14th, with a total of 30 points.
Source : PA
Source: PA