What is the purpose of Object.getOwnPropertyDescriptors()?

Object.getOwnPropertyDescriptors() returns all own property descriptors of an object, including their attributes (value, writable, enumerable, configurable, get, set).

     const obj = {
       name: 'John',
       get fullName() {
         return this.name;
       }
     };

     const descriptors = Object.getOwnPropertyDescriptors(obj);
     console.log(descriptors);
     /*
     {
       name: {
         value: 'John',
         writable: true,
         enumerable: true,
         configurable: true
       },
       fullName: {
         get: [Function: get fullName],
         set: undefined,
         enumerable: true,
         configurable: true
       }
     }
     */
     

Use case 1: Shallow cloning with all property attributes:

     // Regular spread operator loses getters/setters
     const clone1 = { ...obj };

     // Using Object.assign also loses getters/setters
     const clone2 = Object.assign({}, obj);

     // Proper cloning with descriptors
     const properClone = Object.create(
       Object.getPrototypeOf(obj),
       Object.getOwnPropertyDescriptors(obj)
     );
     

Use case 2: Mixin pattern preserving all attributes:

     function mixin(target, ...sources) {
       for (const source of sources) {
         Object.defineProperties(
           target,
           Object.getOwnPropertyDescriptors(source)
         );
       }
       return target;
     }

     const obj1 = {
       get prop() { return 'getter'; }
     };

     const obj2 = {};
     mixin(obj2, obj1);
     console.log(obj2.prop); // 'getter'
     

Use case 3: Inspecting property configuration:

     const obj = {};
     Object.defineProperty(obj, 'readOnly', {
       value: 42,
       writable: false
     });

     const descriptor = Object.getOwnPropertyDescriptors(obj).readOnly;
     console.log(descriptor.writable); // false
     

Comparison with Object.getOwnPropertyDescriptor():

     // Single property
     const singleDesc = Object.getOwnPropertyDescriptor(obj, 'name');

     // All properties
     const allDescs = Object.getOwnPropertyDescriptors(obj);