ES6 无声明的解构赋值

Question

What's the difference between the following syntax? Will the second one generate global variables?

// 1. use let or cont
let [a, b] = [1, 2]

// 2. without using let or const 
[a, b] = [1, 2]

Provide me any official reference would be appreciate.

Answer 1

The first example defines the variables within block scope.

The second example defines the variables globally.

Answer 2

See the MDN pages .

I'd assume that no declaration type would result in the array being initialized like a let , based on what I'm reading here .

let is block scoped and var is function scoped, perhaps you could check this yourself?