To change values in array when using forEach with JavaScript, we can assign the new value.
For instance, we write
const data = [1, 2, 3, 4];
data.forEach((item, i, self) => (self[i] = item + 10));
to call forEach with a callback that has the i and self parameters.
In it, we assign self[i] to the new value of the array.
self is the data array.
i is the index of the entry being iterated through.
item is the entry being iterated through.
