How to Find Duplicate Values in an Array of Objects Using JavaScript?

To find duplicate values in an array of objects in JavaScript, you can use the reduce method along with an object to keep track of the values you have seen so far. If a value is already in the object, it is a duplicate.

Here’s an example:

function findDuplicates(arr) {
  let duplicates = [];
  let seen = {};
  arr.forEach(function(obj) {
    if (!seen[obj.value]) {
      seen[obj.value] = true;
    } else {
      duplicates.push(obj.value);
    }
  });
  return duplicates;
}

let arr = [{value: 1}, {value: 2}, {value: 3}, {value: 2}];
let duplicates = findDuplicates(arr);
console.log("Duplicates: " + duplicates);

In this example, the code defines a function findDuplicates that takes an array arr as an argument. The function uses an object seen to keep track of the values seen so far. If a value is already in the object, it is a duplicate and is pushed into the duplicates array. The function then returns the duplicates array. The code then calls the findDuplicates function with the arr value and logs the result to the console.