var to let/const with empty destructuring

[pionxzh]

The rule var to let/const will not transform empty destructuring.

This is not the code that an average human would write. I noticed this pattern from babel's test case and my codemod test.

Input

var arr = [1,2]
var obj = { name: 'John' }

var [] = arr;
var [first, second] = arr
var {} = obj;
var { name } = obj

Actual Output

const arr = [1,2];
const obj = { name: 'John' };

var [] = arr;
const [first, second] = arr;
var {} = obj;
const { name } = obj;

Expected Output

const arr = [1,2];
const obj = { name: 'John' };

const [] = arr;
const [first, second] = arr;
const {} = obj;
const { name } = obj;

[wirekang]

What is the reason of the empty destructing? Type assertion?

[pionxzh]

I think the main reason why it exist is just because we can, it valid syntax 😮‍💨 And you cannot simply remove the statement as the statement will trigger a [get].

[wirekang]

I didn't mean to be aggressive. I'm wondering why someone/something writes those statements.

[wirekang]

Oh I get a sense that it's a testing for the syntax itself not for specific logic/side-effect, is that correct?

[pionxzh]

yes