Suppose we have an array
a which contains 5 letters.
const a = ['a', 'b', 'c', 'e', 'd']
We want to swap element at index 4 ('d' in this case) with the element at index 3 ('e' in this case).
We can use a temporary item
tmp to store the value of #4, then we put #3 in place of #4, and we assign the temporary item to #3:
const tmp = a a = a a = tmp
Another option, which does not involve declaring a temporary variable, is to use this syntax:
const a = ['a', 'b', 'c', 'e', 'd']; [a, a] = [a, a]
Now the array
a will be correctly ordered as we want.
a //[ 'a', 'b', 'c', 'd', 'e' ]