group-mongo-records-this-week.js

const { ObjectID } = require('mongodb');
const moment = require('moment');

const thisWeek = moment().startOf('isoWeek').unix();

const cursor = db.collection('records').aggregate(
  {
    $project: {
      thisWeek: {
        $cond: {
          if: {
            $gt: ['$_id', ObjectID.createFromTime(thisWeek) ]
          },
          then: true,
          else: false
        }
      },
    }
  },
  {
    $group: {
      _id: {
        thisWeek: '$thisWeek',
      },
      count: {
        $sum: 1
      }
    }
  },
  {
    $project: {
      thisWeek: '$_id.thisWeek',
      count: '$count',
      _id: false
    }
  },
  { cursor: { batchSize: 1 } });

const docs = yield cursor.toArray();

console.log(docs);