https://www.facebook.com/photo/?fbid=163671151879194&set=gm.2865725280192246

example.js

const complaints = Complaints.find({status: 'pending'});

// An object with keys of <Complaint.objectId> and values of {complaint<Complaint>, count<Number>}
// Will dedupe complaints as well as track the number of times they appear.
const complaintStore = complaints.reduce((complaintStore, complaint) => {
    if (complaintStore[complaint.objectId]) {
        // Already encountered this complaint, so just increment the counter
        complaintStore[complaint.objectId].count += 1;
    } else {
        // First time seeing this complaint, so initialize the container and store it
        complaintStore[complaint.objectId] = {
            complaint,
            count: 1,
        };
    }
    return complaintStore;
}, {});

// An array of objects like {complaint<Complaint>, count<Number>}
const finalArray = Object.values(complaintStore);