node-postgres: how to execute “WHERE col IN ()” query?

It looks like you may have been close based on your comment to @ebohlman’s answer. You can use WHERE id = ANY($1::int[]). PostgreSQL will convert the array to the type the parameter is cast to in $1::int[]. So here’s a contrived example that works for me:

var ids = [1,3,4]; 

var q = client.query('SELECT Id FROM MyTable WHERE Id = ANY($1::int[])',[ids]);

q.on('row', function(row) {
  console.log(row);
})

// outputs: { id: 1 }
//          { id: 3 }
//          { id: 4 }