encoded [ i + j ] = '8' , '8' - '0' = 8 8 + 52 = 60 , '8' has 60 th position in char_set .
else if ( encoded [ i + j ] . charCodeAt ( 0 ) >= ' ' . charCodeAt ( 0 ) && encoded [ i + j ] . charCodeAt ( 0 ) <= ' ' . charCodeAt ( 0 ) ) num = num | ( encoded [ i + j ] . charCodeAt ( 0 ) - ' ' . charCodeAt ( 0 ) + 52 ) ;