I used https://gist.github.com/lalkmim/e04845eb9d1c5936622a for help, for a few of them and various other solutions online, just changed for JS.
binary gap - https://app.codility.com/demo/results/training2FAAGH-ADU/
cyclic rotation - https://app.codility.com/demo/results/trainingZ3X2FF-NTW/
odd occurrences in array - https://app.codility.com/demo/results/trainingJRSG7K-8FM/
frog jmp - https://app.codility.com/demo/results/trainingMPZC8R-RZ9/
perm missing element - https://app.codility.com/demo/results/training8VQNBA-NTF/
tape equilibrium - https://app.codility.com/demo/results/trainingHMJHCT-9BX/
frog river one - https://app.codility.com/demo/results/trainingQRCXTS-YNV/
max counters - https://app.codility.com/demo/results/training3G3RN6-PBB/
missing integer - https://app.codility.com/demo/results/trainingC8TMF7-FFG/
perm check - https://app.codility.com/demo/results/trainingK2PZ9F-XK2/
count div - https://app.codility.com/demo/results/training9EANXZ-Q7B/
genomic range query - https://app.codility.com/demo/results/trainingV3ZJH2-KAP/
min average two slice - https://app.codility.com/demo/results/trainingJJGSYF-UTM/
passing cars - https://app.codility.com/demo/results/trainingYWMFSJ-UAK/
distinct - https://app.codility.com/demo/results/trainingS7EH4X-2E8/
max product of three - https://app.codility.com/demo/results/trainingG8WQPN-XMW/
number of distinct intersections - https://app.codility.com/demo/results/trainingUNTTQP-2HX/
triangle - https://app.codility.com/demo/results/trainingKBFVRP-P7A/
brackets - https://app.codility.com/demo/results/trainingGDD63W-BVN/
fish - https://app.codility.com/demo/results/trainingDUPF5V-TFP/
nesting - https://app.codility.com/demo/results/trainingV7XQMP-JSQ/
stone wall - https://app.codility.com/demo/results/trainingKM8XVU-TGY/
dominator - https://app.codility.com/demo/results/trainingHAY9PR-2SR/
equi leader - https://app.codility.com/demo/results/trainingWQXG5Z-42W/
max double slice sum - https://app.codility.com/demo/results/trainingGQRQUC-3VT/
max profit - https://app.codility.com/demo/results/training2SDP6J-GFJ/
max slice sum - https://app.codility.com/demo/results/trainingDTWD3H-NMY/
count factors - https://app.codility.com/demo/results/trainingFV4PS4-VNX/
flags - https://app.codility.com/demo/results/trainingBPW263-2GT/
min perimeter rectangle - https://app.codility.com/demo/results/trainingCBKYNW-XY6/
peaks - https://app.codility.com/demo/results/trainingHFJ33K-RYQ/
count non divisible - https://app.codility.com/demo/results/trainingWTK9H2-CHU/
count semi-primes - https://app.codility.com/demo/results/trainingZD8TJZ-BTX/
chocolates by numbers - https://app.codility.com/demo/results/trainingRJCQDF-5BX/
common prime divisors - https://app.codility.com/demo/results/trainingJJMR3Y-79U/
fib frog - https://app.codility.com/demo/results/trainingP3HSGV-43Z/
ladder - https://app.codility.com/demo/results/trainingH9SWV3-C89/
min max division - https://app.codility.com/demo/results/trainingSZ7XJG-C3F/
nailing planks - https://app.codility.com/demo/results/training8FB54J-RMS/
abs distinct - https://app.codility.com/demo/results/training4BZB4N-X4A/
count distinct slices - https://app.codility.com/demo/results/trainingSPUMYF-RMW/
count triangles - https://app.codility.com/demo/results/training986YYW-HMR/
min abs sum of two - https://app.codility.com/demo/results/trainingGB4WAX-2HU/
max non-overlapping slices - https://app.codility.com/demo/results/training94QWAN-9SB/
tie ropes - https://app.codility.com/demo/results/trainingDXN6WX-WWT/
min abs sum - https://app.codility.com/demo/results/trainingYQQ4PK-DXH/
number solitaire - https://app.codility.com/demo/results/trainingTS4QDV-34X/
flood depth - https://app.codility.com/demo/results/trainingNDVWCW-478/
longest password - https://app.codility.com/demo/results/trainingZU9C6P-C8E/
slalom skiing - https://app.codility.com/demo/results/training5ZQKUV-66Z/ ### needs optimisation
dwarfs rafting - https://app.codility.com/demo/results/training48DMVS-9ZE/
hilbert maze - ### WIP
rectangle builder greater area - https://app.codility.com/demo/results/training29K2SQ-HVT/
tree product - ### WIP
array recovery - ### WIP
diamonds count - https://app.codility.com/demo/results/training9WD44T-CTR/ ### needs optimisation
socks laundering - https://app.codility.com/demo/results/trainingCGKTMW-ZPV/
tennis tournament - https://app.codility.com/demo/results/training6MPCJE-CB3/
array inversion count - https://app.codility.com/demo/results/trainingFNXB4Y-GMH/
polygon concavity index - https://app.codility.com/demo/results/trainingP7EKFC-XJ7/
str symmetry point - https://app.codility.com/demo/results/training53T27D-P32/
tree height - https://app.codility.com/demo/results/trainingAXVA25-YEV/ (quick answer https://app.codility.com/demo/results/trainingQMG2QK-Z4K/ yay strings)