find duplicate values in array of objects javascript code example

Example 1: how to find duplicate item in array of object in javascript

const values = [
  { name: 'someName1' },
  { name: 'someName2' },
  { name: 'someName3' },
  { name: 'someName1' }
]

const uniqueValues = new Set(values.map(v => v.name));

if (uniqueValues.size < values.length) {
  console.log('uniqueValues')
}

Example 2: array of objects how to check if property has duplicate

var yourArray = [

{Index: 1, Name: "Farley, Charley", EmployeeCode: "12", PaymentType: "Void", CheckDate: "01/04/2012"},
{Index: 2, Name: "Farley, Charley", EmployeeCode: "12", PaymentType: "Void", CheckDate: "01/04/2012"},
{Index: 3, Name: "Tarley, Charley", EmployeeCode: "12", PaymentType: "Void", CheckDate: "01/04/2012"}
];

   unique = [...new Set(yourArray.map(propYoureChecking => propYoureChecking.Name))];
if (unique.length === 1) {
console.log(unique);
}

Example 3: js check if array of objects contains duplicates

const arrayOfObjCopy = [...arrayOfObj];

Object.keys(arrayOfObjCopy).forEach((key) => {
  arrayOfObjCopy[key] = JSON.stringify(arrayOfObjCopy[key]);
 });

const arrayOfObjhasDuplicates = uniq(arrayOfObjCopy).length != arrayOfObjCopy.length;

Example 4: find duplicates in an object array

npm i find-array-duplicates

import duplicates from 'find-array-duplicates'

const names = [
 { 'age': 36, 'name': 'Bob' },
 { 'age': 40, 'name': 'Harry' },
 { 'age': 1,  'name': 'Bob' }
]
 
duplicates(names, 'name').single()
// => [{ 'age': 36, 'name': 'Bob' }]