How do you plan to solve it?
module jk_ff ( input CLK, input J, input K, output reg Q ); always@(posedge CLK) begin if(J==0 && K==0) Q<=Q; else if (J==0 && K==1) Q<=1'b0; else if(J==1 && K==0) Q<=1'b1; else Q<=~Q; end endmodule