JavaScript Interview Question #189

What is metaprogramming in JavaScript?

Advanced JavaScript, Practical Problems & Senior Interview Scenarios Senior Advanced

Quick Interview Answer

Metaprogramming is code that inspects, modifies, or controls the behavior or structure of other code and objects. JavaScript supports metaprogramming through features such as property descriptors, symbols, Proxy, Reflect, and dynamic property access.

Detailed Explanation

It is useful for frameworks, serialization, validation, dependency systems, and tooling, but excessive metaprogramming can make application behavior difficult to trace and debug.

Code Example

const product = {
    id: 1,
    name: "Keyboard"
};

for (const key of Reflect.ownKeys(product)) {
    console.log(
        key,
        Reflect.get(product, key)
    );
}