javascript - Interesting behavior about ES6 array destructuring and swapping

Question

I just noticed that the following code, without immediately referencing one after let [one, two] = [1, 2], trying [one, two] = [two, one] would crash:

let [one, two, three] = [1, 2, 3]
[one, two] = [two, one] // CRASH! one is not defined
console.log(one, two)

Answer 1

Add a semicolon to the 1st line, because the interpreter assumes that lines 1 and 2 declarations happen together, and one (and two) is not defined yet:

let [one, two, three] = [1, 2, 3];
[one, two] = [two, one]
console.log(one, two)