Is there a way to do multiple assignment and initialization with block scope?

Question

I would like to declare two variables with block scope and initialize them to the same value. It would be nice if the following worked that way but it doesn't...

{
  let a = b = "wang";
}
console.log("b:", b);

Variable 'a' has block scope but variable 'b' doesn't, it has function scope as if it were declared with a var.

Is there a one line* way of accomplishing this or do I have to do...

let a, b;
a = b = "wang";

---

* not that I would throw readability under a bus to save a couple of chars you understand, I'm just curious!

Answer 1

You can do it in a single let declaration as follows:

{
  let a = "wang", b = a;
}
console.log("b:", b); //undefined or ReferenceError

Because both a and b are declared with let inside the braces, they both get block scope. You have to assign a first so that it's been assigned before you assign it to b also.

Answer 2

You can use array destructuring with fill to avoid repeating the value:

{
  let [a, b, c, d] = Array(4).fill("wang");
  console.log(a, b, c, d); // "wang", "wang", "wang", "wang"
}
a; // ReferenceError

If you don't want to bother about the number of variables and don't want to allocate big arrays, you can also use an immediately invoked generator function expression. For simplicity, it may be a good idea to implement this as a helper function

const repeat = function*(value){while(true) yield value};
{
  let [a, b, c, d] = repeat("wang");
  console.log(a, b, c, d); // "wang", "wang", "wang", "wang"
}
a; // ReferenceError