let x, { x: y = 1 } = { x }; y;
(function() {
let f = this ? class g { } : class h { };
return [ typeof f, typeof h ];
})();
[...[...'...']].length
typeof (function* f() { yield f })().next().next()
let a = 12, b = 3;
[a, b] = [b, a];
class Slave { // ... };
const slave = Slave();
const [a, , b] = [1, 2, 3];
console.log(a, b);