Loops, and where your data lives
INPUT · Slides
01 / 04
fruits[1] got you the second item. Put that same writing on the left of an = and you can put a new value there.
The shape is array[number] = new value;. Exactly the same thinking as updating a variable.
const fruits = ["apple", "orange", "peach"];fruits[1] = "grape";console.log(fruits);Result
["apple", "grape", "peach"]
02 / 04
When you write over it, the old value does not stay. What is at that position is simply replaced.
The positions you did not touch stay as they were. Only the number you named changes.
const nums = [10, 20, 30];nums[0] = 99;console.log(nums[0]);console.log(nums[1]);Result
99 20
03 / 04
This one may surprise you. Even an array made with const, you can change the contents of.
What const forbids is "putting something else under that name", not "reaching into the container". So arrays are normally made with const.
const list = ["a", "b"];list[0] = "z";console.log(list);Result
["z", "b"]
04 / 04
Just as with variables, you can put the current value on the right. Shorthand like += works here as well.
That gets you things like adding to a score or taking down some stock.
const scores = [80, 60];scores[0] = scores[0] + 10;scores[1] += 5;console.log(scores);Result
[90, 65]