Merge array elements group by properties in Javascript

June 30, 2022

I have the following javascript object array:

       [ { "firstName": "x", "lastName": "y", "age": 10}, 
         { "firstName": "x", "lastName": "y", "height": 100},
         { "firstName": "x", "lastName": "y", "weight": 50},
         { "firstName": "a", "lastName": "b", "age": 11}, 
         { "firstName": "a", "lastName": "b", "height": 110},
         { "firstName": "a", "lastName": "b", "weight": 60},
         { "firstName": "m", "lastName": "n", "age": 12}, 
         { "firstName": "m", "lastName": "n", "height": 120},
         { "firstName": "m", "lastName": "n", "weight": 70}]

Is it possible to group by firstName and lastName such that it includes other properties of the object in the array?

Expected Array:

       [ { "firstName": "x", "lastName": "y", "age": 10, "height": 100, "weight": 50}, 
         { "firstName": "a", "lastName": "b", "age": 11, "height": 110, "weight": 60},
         { "firstName": "m", "lastName": "n", "age": 12, "height": 120, "weight": 70}]

>Solution :

Concept

Prepare a result array. Iterate through all the data. Check if the firstName and lastName exist in the result array. If no, push it into the result array. If yes, merge the object to get the missing properties.

Code

const data =[ { "firstName": "x", "lastName": "y", "age": 10}, 
         { "firstName": "x", "lastName": "y", "height": 100},
         { "firstName": "x", "lastName": "y", "weight": 50},
         { "firstName": "a", "lastName": "b", "age": 11}, 
         { "firstName": "a", "lastName": "b", "height": 110},
         { "firstName": "a", "lastName": "b", "weight": 60},
         { "firstName": "m", "lastName": "n", "age": 12}, 
         { "firstName": "m", "lastName": "n", "height": 120},
         { "firstName": "m", "lastName": "n", "weight": 70}];
let result = [];
let found;
data.forEach(d => {
  found = false;
  result.forEach(r => {
    if (r.firstName === d.firstName && r.lastName === d.lastName){
      Object.assign(r, d);
      found = true;
    }
  });
  if (!found){
    result.push(d);
  }
});
console.log(result);