# Adding up identical elements in JavaScript

JavascriptWeb DevelopmentFront End TechnologyObject Oriented Programming

We are required to write a JavaScript function that takes in an array of Numbers and sums all the identical numbers together at one index.

## For example

If the input array is −

const arr = [20, 10, 15, 20, 15, 10];

Then the output should be −

const output = [40, 20, 30];

Therefore, let’s write the code for this function −

## Example

The code for this will be −

const arr = [20, 10, 15, 20, 15, 10];
const addSimilar = arr => {
for(let i = 0; i < arr.length; i++){
while(i !== arr.lastIndexOf(arr[i])){
const ind = arr.lastIndexOf(arr[i]);
arr[i] += arr.splice(ind, 1)[0];
};
};
};
console.log(arr);
[ 40, 20, 30 ]