javascript array duplicate check by key value code example

Example 1: 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 2: 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' }]