gistfile1.js

// Suppose needed_category = [1,2,3]

r.db('foo').table('bar')
    .filter( function(movie) {
        r.expr( needed_category ).map( function(category) {
            return category.eq(movie('category');
        }).redunce( function(left, right)
            return left.or(right);
        }, false)
    }).run( connection, function(err, cursor) { ... } )