JavascriptWeb DevelopmentFront End TechnologyObject Oriented Programming

We are required to write a JavaScript function that takes in an array of numbers and returns the alternative multiplicative sum of the elements.

For example: If the array is −

const arr = [1, 2, 3, 4, 5, 6, 7];

Then the output should be calculated like this −

1*2+3*4+5*6+7
2+12+30+7

And the output should be −

51

Let’s write the code for this function −

## Example

The code for this will be −

const arr = [1, 2, 3, 4, 5, 6, 7];
const alternateOperation = arr => {
const productArr = arr.reduce((acc, val, ind) => {
if(ind % 2 === 1){
return acc;
};
acc.push(val * (arr[ind + 1] || 1));
return acc;
}, []);
return productArr.reduce((acc, val) => acc + val);
};
console.log(alternateOperation(arr));

## Output

The output in the console −

51
Updated on 15-Oct-2020 09:00:59