Function for finding elements which are there in a [ ] but not in b [ ] .
function findMissing ( a , b , n , m ) { for ( let i = 0 ; i < n ; i ++ ) { let j ; for ( j = 0 ; j < m ; j ++ ) if ( a [ i ] == b [ j ] ) break ; if ( j == m ) document . write ( a [ i ] + " " ) ; } }