javascript csvBuilder to output results of mongo query as csv

csvBuilder_example.js

// Usage: mongo localhost:27017/test csvBuilder_example.js | awk 'NR > 3 { print }' > products.out

var c = db.products.find({}, { _id: 1, name: 1, type: 1, shipper: 1 }); 

function printCsv(c) {
  while (c.hasNext()) {
    var r = c.next();
    print(csvBuilder().
      add(r._id).
      add(r.name).
      add(r.type).
      add(r.shipper['$id']).
      build());
  }
}

function csvBuilder() {
  var data = '',
      builder = {
        add: function(field) {
          if (data.length > 0) data += ','; 
          data += '"';
          if (field === null || field === undefined) {
            data += '';
          } else if (typeof field == 'string' || field instanceof String) {
            data += field.replace(/"/g, '""');
          } else {
            data += field;
          }
          data += '"'; 
          return builder;
        },
        build: function() {
          return data;
        }
      };
  return builder;
}

print('p_id,p_name,p_type,p_shipper_id');

printCsv(c);