The one I always forget is
```js
const { a: a1, b: b1 } = obj;
```
where the *key* is the member name in `obj` and the *value* is what we want to call it.

From [mozilla.org](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment)
```js
const [a, b] = array;
const [a, , b] = array;
const [a = aDefault, b] = array;
const [a, b, ...rest] = array;
const [a, , b, ...rest] = array;
const [a, b, ...{ pop, push }] = array;
const [a, b, ...[c, d]] = array;

const { a, b } = obj;
const { a: a1, b: b1 } = obj;
const { a: a1 = aDefault, b = bDefault } = obj;
const { a, b, ...rest } = obj;
const { a: a1, b: b1, ...rest } = obj;
const { [key]: a } = obj;

let a, b, a1, b1, c, d, rest, pop, push;
[a, b] = array;
[a, , b] = array;
[a = aDefault, b] = array;
[a, b, ...rest] = array;
[a, , b, ...rest] = array;
[a, b, ...{ pop, push }] = array;
[a, b, ...[c, d]] = array;

({ a, b } = obj); // brackets are required
({ a: a1, b: b1 } = obj);
({ a: a1 = aDefault, b = bDefault } = obj);
({ a, b, ...rest } = obj);
({ a: a1, b: b1, ...rest } = obj);
```

## Destructuring without `var`, `let` or `const`
From [this stackoverflow](https://stackoverflow.com/questions/27386234/object-destructuring-without-var-let-or-const)
```
// use () grouping
let a,b
( [a,b] = [1,2] )
let o = { a:3, b:4 }
( {a,b} = o )
```
This is useful when we want to set scope with `let`, but then want to destructure
differently in different branches of `if-else`.