find duplicate values in array object javascript
function getUnique(arr, comp) {
// store the comparison values in array
const unique = arr.map(e => e[comp])
// store the indexes of the unique objects
.map((e, i, final) => final.indexOf(e) === i && i)
// eliminate the false indexes & return unique objects
.filter((e) => arr[e]).map(e => arr[e]);
return unique;
}
console.log(getUnique(arr,'id'));