Backspace in WebTerminal

I try to run a small test routine (guessing a random number) in WebTerminal but the result looks broken.
in IRISterminal:

 in WebTerminal:

I think it relates to backspace.
Is there some special setting required?

The code:

a
 s q=".......... guess [0..9]: " 
 f i=1:1 d b if p w ! w $c(9),"thank you",! q
 q  
b
 w !,i,$c(9),q
 f  r v#1 q:(v?.1n) w " !no number",$c(8,8,8,8,8,8,8,8,8,8,8,8)
 w " "
 s r=$R(10),p=$s(v="":1,v=r:"!",v>r:"<",1:">")
 s x=q,$e(x,r+1)="*",$e(x,v+1)=$s(v=r:"!",v>r:"<",1:">") 
 q:p  w $c(13),$c(9),x s p=v=r q