Combining same objects in json array javascript

Question

I have this array:

[{ "id": 1, "myId": "100", "name": "amey" }, { "id": 2, "myId": "100", "name": "anuj" }, { "id": 3, "myId": "101", "name": "suraj" }, { "id": 4, "myId": "101", "name": "suraj h" }]

I want output like this:

[{ "id": 1, "myId": "100", "name": ["amey", "anuj"] }, { "id": 3, "myId": "101", "name": ["suraj", "suraj h] }]

How can I do this using javascript

for (var i = 0; i < myarray.length; i++) {
  //And loop again for duplicate data
  for (var j = i + 1; j < myarray.length; j++) {
    if (
      myarray[i].VENDOR_ID == myarray[j].VENDOR_ID &&
      myarray[i].ORDER_ID === myarray[j].ORDER_ID
    ) {
      var tmp = myarray[j].NAME;
      console.log(tmp);
      myarray[j].NAME = [];
      myarray[j].NAME.push(tmp);
      myarray[j].NAME.push(myarray[i].NAME);
      myarray[i] = {};
    }
  }
}

question from:https://stackoverflow.com/questions/65841673/combining-same-objects-in-json-array-javascript

Answer 1

You can use an array reduce into an object and return the array of values. Reduce into an object using the myId property as the key to group by. Shallow copy any existing state and and name array, appending the new name value from the current element.

Object.values(
  input.reduce(
    (acc, { id, myId, name }) => ({
      ...acc,
      [myId]: {
        ...(acc[myId] || { id, myId }),
        name: [...(acc[myId]?.name || []), name]
      }
    }),
    {}
  )

const input = [
  { id: 1, myId: "100", name: "amey" },
  { id: 2, myId: "100", name: "anuj" },
  { id: 3, myId: "101", name: "suraj" },
  { id: 4, myId: "101", name: "suraj h" }
];

const res = Object.values(
  input.reduce(
    (acc, { id, myId, name }) => ({
      ...acc,
      [myId]: {
        ...(acc[myId] || { id, myId }),
        name: [...(acc[myId]?.name || []), name]
      }
    }),
    {}
  )
);

console.log(JSON.stringify(res));