Sum identical elements within one array in JavaScript

We are required to write a JavaScript function that takes in an array of Numbers.

The array might contain some repeating / duplicate entries within it. Our function should add all the duplicate entries and return the new array thus formed.

Example

The code for this will be −

const arr = [20, 20, 20, 10, 10, 5, 1];
const sumIdentical = (arr = []) => {
   let map = {};
   for (let i = 0; i 
Output
And the output in the console will be −
[ 1, 5, 20, 60 ]