Every property in JavaScript has a property descriptor — an object that describes its behavior. The three main attributes are writable, enumerable, and configurable.

flowchart TD
    A["Property Descriptors"]
    B["writable: Can value be changed?"]
    C["enumerable: Shows up in loops?"]
    D["configurable: Can descriptor be changed?"]

    A --> B
    A --> C
    A --> D

const user = { name: 'Alice' };

const descriptor = Object.getOwnPropertyDescriptor(user, 'name');
// { value: 'Alice', writable: true, enumerable: true, configurable: true }

• writable — true if the value can be changed
• enumerable — true if it appears in for...in and Object.keys()
• configurable — true if the descriptor can be changed or property deleted

• Every property has a descriptor with 3 boolean flags
• writable — can the value change?
• enumerable — does it appear in iteration?
• configurable — can the descriptor be modified?

• MDN: Property Descriptors