Object Descriptors & Property Flags

What happens when attempting to delete a non-configurable property?

const config = {};
Object.defineProperty(config, 'API_KEY', {
  value: 'abc123',
  writable: false,
  enumerable: false,
  configurable: false
});

delete config.API_KEY;
console.log(config.API_KEY);

undefined
null
'abc123'
The console will log 'abc123' because: 1) The API_KEY property is defined as non-configurable, 2) Non-configurable properties cannot be deleted, so delete config.API_KEY fails silently in non-strict mode, 3) The property remains intact with its original value, 4) This combination of flags (non-writable, non-enumerable, non-configurable) creates a completely locked property, 5) Such properties are ideal for constants and critical configuration values, 6) This is the strongest form of property protection in JavaScript objects.
Error will be thrown

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