Consecutive elements sum array in JavaScript

We are required to write a JavaScript function that takes in an array of Numbers and returns a new array with elements as the sum of two consecutive elements from the original array.

For example, if the input array is ?

const arr1 = [1, 1, 2, 7, 4, 5, 6, 7, 8, 9];

Then the output should be ?

const output = [2, 9, 9, 13, 17]

How It Works

The function pairs consecutive elements: (1+1=2), (2+7=9), (4+5=9), (6+7=13), (8+9=17). If the array has an odd length, the last element is paired with 0.

Example

The code for this will be ?

const arr1 = [1, 1, 2, 7, 4, 5, 6, 7, 8, 9];

const consecutiveSum = arr => {
    const res = [];
    for(let i = 0; i 

Output

The output in the console ?

[ 2, 9, 9, 13, 17 ]


Handling Odd-Length Arrays

When the array has an odd number of elements, the last element gets paired with 0:

const oddArray = [1, 2, 3, 4, 5];
console.log(consecutiveSum(oddArray));


[ 3, 7, 5 ]


Alternative Approach Using map()

Here's a more functional programming approach:

const consecutiveSumMap = arr => {
    return arr.filter((_, i) => i % 2 === 0)
             .map((val, i) => val + (arr[i * 2 + 1] || 0));
};

const arr2 = [2, 4, 6, 8, 10];
console.log(consecutiveSumMap(arr2));


[ 6, 14, 10 ]


Conclusion

Both approaches effectively sum consecutive pairs in an array. The for-loop method is more straightforward, while the map() approach follows functional programming principles. Choose based on your coding style preference.