How to compare elements of an array and merge based on a condition?

Question

I have the below sample array.(original array has more than 200 elements)

var array = [
  {
    "clientid": "ID000002",
    "accesstoken": "pllALEl3TlwLL9hHP938H",
    "groupname": "ABC",
    "ancestorid": "8982857550",
    "stroyid": [
      "IGN-EXM-001-PDF",
      "IGN-EXM-002-PDF"
    ]
  }, {
    "clientid": "ID000002",
    "accesstoken": "pllALEl3TlwpHOD4aTP38H",
    "groupname": "EFG",
    "ancestorid": "4705872914",
    "stroyid": [
      "APP-ENE-FIE-CON",
      "APP-ENE-ASS-INS",
      "APP-ENE-ASS-CAR",
      "APP-ENE-MAT-REA"
    ]
  }, {
    "clientid": "ID000002",
    "accesstoken": "pllALEl3TlwLL9hHP938H",
    "groupname": "ABC",
    "ancestorid": "8982857550",
    "stroyid": [
      "IGN-EXM-001-ZIP",
      "IGN-EXM-002-ZIP"
    ]
  }
]

Condition = if (client id && ancestor id are the same then merge the storyid) so the output should be like:

[{
  "clientid": "ID000002",
  "accesstoken": "pllALEl3TlwLL9hHP938H",
  "groupname": "ABC",
  "ancestorid": "8982857550",
  "stroyid": [
    "IGN-EXM-001-PDF",
    "IGN-EXM-002-PDF",
    "IGN-EXM-001-ZIP",
    "IGN-EXM-002-ZIP"

  ]
}, {
  "clientid": "ID000002",
  "accesstoken": "pllALEl3TlwpHOD4aTP38H",
  "groupname": "EFG",
  "ancestorid": "4705872914",
  "stroyid": [
    "APP-ENE-FIE-CON",
    "APP-ENE-ASS-INS",
    "APP-ENE-ASS-CAR",
    "APP-ENE-MAT-REA"
  ]
}]

Please help me with javascript code to achieve this.

Answer 1

With plain Javascript, you could use a hash table as closure for grouping with clientid and ancestorid.

stroyid gets filtered for unique values.

var array = [{ clientid: "ID000002", accesstoken: "pllALEl3TlwLL9hHP938H", groupname: "ABC", ancestorid: "8982857550", stroyid: ["IGN-EXM-001-PDF", "IGN-EXM-002-PDF", "dupe"] }, { clientid: "ID000002", accesstoken: "pllALEl3TlwpHOD4aTP38H", groupname: "EFG", ancestorid: "4705872914", stroyid: ["APP-ENE-FIE-CON", "APP-ENE-ASS-INS", "APP-ENE-ASS-CAR", "APP-ENE-MAT-REA"] }, { clientid: "ID000002", accesstoken: "pllALEl3TlwLL9hHP9n", groupname: "ABC", ancestorid: "8982857550", stroyid: ["IGN-EXM-001-ZIP", "IGN-EXM-002-ZIP", "dupe"] }],
    result = array.reduce(function (hash) {
        return function (r, a) {
            var key = [a.clientid, a.ancestorid].join('|');
            if (!hash[key]) {
                hash[key] = { clientid: a.clientid, accesstoken: a.accesstoken, groupname: a.groupname, ancestorid: a.ancestorid, stroyid: a.stroyid };
                return r.concat(hash[key]);
            }
            hash[key].stroyid = hash[key].stroyid.concat(a.stroyid).filter(function (temp) {
                return function (a) {
                    return !temp[a] && (temp[a] = true);
                };
            }(Object.create(null)));
            return r;
        };
    }(Object.create(null)), []);
    
console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

const myArray = [
  { clientid: 1, ancestorid: 1, stroyid: ['a', 'b', 'c'] },
  { clientid: 1, ancestorid: 1, stroyid: ['a', 'b', 'd', 'e'] },
];

const newArray = myArray.reduce((newArray, entry) => {
  // Find if there is a duplicate in the new array
  const duplicate = newArray.find(newEntry => (
    entry.clientid === newEntry.clientid && entry.ancestorid === newEntry.ancestorid
  ));

  // If there is a duplicate, merge their stroyids
  if (duplicate) {
    const cleanIDs = entry.stroyid.filter(id => !duplicate.stroyid.includes(id));
    duplicate.stroyid = duplicate.stroyid.concat(cleanIDs);
  }
  else newArray.push(entry); // Else, add the entire entry

  return newArray;
}, []);

console.log(newArray);