Object Descriptors & Property Flags

What design pattern is demonstrated here?

// Define library functionality
const myLibrary = {};

// Public API
Object.defineProperties(myLibrary, {
  version: {
    value: '1.0.0',
    writable: false,
    enumerable: true
  },
  calculate: {
    value: function(x) { return x * 2; },
    writable: false,
    enumerable: true
  }
});

// Internal utilities
Object.defineProperties(myLibrary, {
  _helpers: {
    value: {
      format: x => `Result: ${x}`
    },
    enumerable: false
  }
});

Factory pattern
Singleton pattern
Module pattern with public/private API separation
This code demonstrates the module pattern with public/private API separation: 1) It creates a clear distinction between public and private parts of the library, 2) Public properties (version, calculate) are made enumerable for discoverability, 3) Internal utilities (_helpers) are non-enumerable to hide them from normal enumeration, 4) All properties are non-writable to prevent modification, 5) The use of property descriptors provides fine-grained control over the interface, 6) This pattern is common in JavaScript libraries that need to expose a clean API while hiding implementation details, 7) The naming convention with underscore (_helpers) further signals internal use only.
Observer pattern

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