Modulo the number found in the String by 26
decrypted_str += String . fromCharCode ( ' ' . charCodeAt ( 0 ) + modulo_by_26 ( num_found_so_far ) ) ; num_found_so_far = " " ; } } if ( num_found_so_far . length > 0 ) { decrypted_str += String . fromCharCode ( ' ' . charCodeAt ( 0 ) + modulo_by_26 ( num_found_so_far ) ) ; } return decrypted_str ; }