JSFiddle - React, Tailwind, and code Playground

by nkdweb

JavaScript

const beneficiaryArr = [{'orgId':'Mike'}, {'orgId':'Matt'}, {'orgId':'Nancy'},{'orgId': 'Adam'}, {'orgId':'Jenny'}, {'orgId':'Nancy'}, {'orgId':'Carl'}]

const lookup = beneficiaryArr.reduce((a, e) => {
        a[e.orgId] = 1 + a[e.orgId] || 0
        return a
    }, {})
    const duplicates = beneficiaryArr.filter(e => lookup[e.orgId])
    console.log(duplicates)