Write a javascript that find and display number of duplicate values in an array

1. How to find duplicate number in array JavaScript?
2. How do you find the number of duplicates in an array?

How to find duplicate number in array JavaScript?

Using the filter() and indexOf() Methods

This is the shortest and the easiest way of finding duplicates in an array, where the filter() method traverses the array and filters items according to the defined condition and returns a new array, while the indexOf() gives the index of the passed item.

How do you find the number of duplicates in an array?

Duplicate elements can be found using two loops. The outer loop will iterate through the array from 0 to length of the array. The outer loop will select an element. The inner loop will be used to compare the selected element with the rest of the elements of the array.