1.by jefTime(1,leftCode)
2.by jefTime(2,leftCode)
3.by transpileTime(3,leftCode)
4.by transpileTime(4,leftCode)
5.by js1Time(5,leftCode)
6.by js2Time(6,leftCode)
after clicking button, to wait until done needs several minutes
jefTime(1,"  0 4000000 for 1+ next .") needs 7581 ms
jefTime(2,": x 4000000 for 1+ next . ; 0 x") needs 2719 ms
transpileTime(3,"  0 4000000 for 1+ next .") needs 64 ms
transpileTime(4,": x 4000000 for 1+ next . ; 0 x") needs 56 ms
js1Time(-1,"i=4000000,n=0;while(i-->=0){n++};console.log(n)") needs 967 ms
js2Time(-1,"i=4000000,n=0;while(i-->=0){n++};console.log(n)") needs 968 ms