how to make an array cumulative code example
Example: javascript array of cumulative sum
const accumulate = arr => arr.map((sum => value => sum += value)(0));
// Example
accumulate([1, 2, 3, 4]); // [1, 3, 6, 10]
// 1 = 1
// 1 + 2 = 3
// 1 + 2 + 3 = 6
// 1 + 2 + 3 + 4 = 10