Destructuring & Spread Operator

const [a, [b, c]] = [1, [2, 3]];
const {a, {b, c}} = {a: 1, {b: 2, c: 3}};
const {a, b: {c, d}} = {a: 1, b: 2, c: 3, d: 4};
const {a, b: {c, d}} = {a: 1, b: {c: 2, d: 3}};
The valid use of nested destructuring is `const {a, b: {c, d}} = {a: 1, b: {c: 2, d: 3}};`. This syntax correctly destructures a nested object, extracting the property `a` from the top level, and properties `c` and `d` from the nested object at property `b`. After this destructuring, the variables would be: `a = 1`, `c = 2`, and `d = 3` (note that there's no variable named `b` created). Nested destructuring is useful when working with complex data structures like API responses or configuration objects. It allows you to extract deeply nested values in a single statement. Option 1 is valid for arrays but not marked as correct here. Option 2 has invalid object syntax. Option 3 is incorrect because the structure doesn't match the data (it tries to destructure properties from `b` as if it were an object, but `b` is just a number in this example).