What are updated array values not saved to array in for each loop

Question

js
https://code.sololearn.com/cBNYT6gTAk2O/?ref=app

Answer 1

because the 'element' variable only hold the value of each items, not the array reference ^^

to update the array using forEach method, use other callback arguments:

arr.forEach((value,index,array) => {
if (value>15) array[index] += 2;
});

Answer 2

however, you could assign to arr a mapping of arr:

arr = arr.map(
val => val>15 ? val + 2 : val
);