Bug in your Code?

Question

This sample code seems to have a bug. After the first line, a and b are 'undefined'.
Is that the intention?

ES6 Destructuring:
The destructuring syntax also simplifies assignment and swapping values:
let a, b, c = 4, d = 8;
[a, b = 6] = [2]; // a = 2, b = 6

[c, d] = [d, c]; // c = 8, d = 4

Answer 1

Yes, unlike c and d they aren't given a value until the 2nd line which is 1 example of using destructuring.
3rd line is another example.

Answer 2

John Weiss

ChaoticDawg explanation is correct
https://code.sololearn.com/WF9Q4rj057mW/?ref=app

Answer 3

there is no bug