Oh right - that makes sense sorry I didn't think of that

Thank you for your help :) :)

Thanks for your response could you explain please where I am going wrong with this one

Expected 'true' on input of

8 7 1 7 6 4 1 4 2

7 6 4 1 5 8 4 9 7

1 4 2 7 9 7 8 1 3

7 1 4 6 5 9 4 8 7

6 5 9 5 7 3 9 3 9

4 8 7 9 3 9 1 3 8

1 4 8 4 9 1 2 7 3

4 9 1 8 3 3 7 9 8

2 7 3 7 9 8 3 8 4

Lots of the testcases are not correct in javascript!

Suprised so many have upvoted this. Concatination is slow and it does not work for non ASCII strings.