Groups array entries based on given path. Uses getProperty function (https://gist.github.com/alexkhismatulin/0dee70114e597a32bcd59c6acc934d79)

groupBy.js

const groupBy = (arr, path) => {
  if (!path || typeof path !== "string") return {}

  return Object.keys(arr).reduce((accum, key) => {
    const value = getProperty(arr[key], path)

    if (accum[value]) return { ...accum, [value]: [...accum[value], arr[key]] }

    return { ...accum, [value]: [arr[key]] }
  }, {})
}



// example
const dataset = [
  {
    name: "Arsen",
    passport: {
      issuedAt: "2019",
    },
  },
  {
    name: "Alex",
    passport: {
      issuedAt: "2016",
    },
  },
  {
    name: "John",
    passport: {
      issuedAt: "2019",
    },
  },
]

console.log(groupBy(dataset, "passport.issuedAt"))
/*
Output: 
{
  2016: [
    {
      name: "Alex",
      passport: {
        issuedAt: "2016",
      },
    },
  ],
  2018: [
    {
      name: "Arsen",
      passport: {
        issuedAt: "2019",
      },
    },
    {
      name: "John",
      passport: {
        issuedAt: "2019",
      },
    },
  ],
}
*/