JS: Get duplicate values in an array of objects

readme.md

usage

dupes([{ name: 'x' }, { name: 'x' }, { name: 'y' }, { name: 'z' }], 'name')

dupes.js

const dupes = (arr, key) => {
  const map = {}
  const result = []

  arr.forEach((obj) => {
    const value = obj[key]
    if (map[value]) result.push(obj)
    map[value] = true
  })

 return result
}