Why is this not valid when using the new es6 destructuring syntax
var a, b, c;
{a, b, c } = {a:1, b:2, c:3};
when this is:
var {a, b, c } = {a:1, b:2, c:3};
console.log(a, ' ', b, ' ',c);
and so is this:
var a = 1;
var b = 3;
[a, b] = [b, a];
I had a read of the MDN documentataion and I see no mention of the syntax I'm attempting and I assume there must be a good reason, I'm just trying to understand why.
In your example, the first { is ambiguous and the parser will interpret it as the beginning of a block. While {a, b, c} is a valid block, the following assignment operator is not valid.
Wrap everything in parenthesis and it will parse correctly:
({a, b, c} = {a:1, b:2, c:3});
This is similar to having an object literal by itself (for whatever reasons):
{"a": 42} // parse error
({"a": 42}) // works
Invalid left-hand side in assignment when doing that. ({a, b, c} = {a: 1, b: 2, c: 3}); works for me.
