text: countP [ ] : Store count of all characters of pattern countTW [ ] : Store count of current window of text
code: let countP = new Array ( 256 ) ; let countTW = new Array ( 256 ) ; for ( let i = 0 ; i < 256 ; i ++ ) { countP [ i ] = 0 ; countTW [ i ] = 0 ; } for ( let i = 0 ; i < 256 ; i ++ ) { countP [ i ] = 0 ; countTW [ i ] = 0 ; } for ( let i = 0 ; i < M ; i ++ ) { ( countP [ pat [ i ] . charCodeAt ( 0 ) ] ) ++ ; ( countTW [ txt [ i ] . charCodeAt ( 0 ) ] ) ++ ; }