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Version: 3.28.0

handler.getOwnPropertyDescriptor()

The handler.getOwnPropertyDescriptor() method is a trap for Object.getOwnPropertyDescriptor().

Syntax​

new Proxy(target, {
  getOwnPropertyDescriptor(target, prop) {
  }
});

Parameters​

The following parameters are passed to the getOwnPropertyDescriptor() method. this is bound to the handler.

  • target
    • : The target object.
  • prop
    • : The name of the property whose description should be retrieved.

Return value​

The getOwnPropertyDescriptor() method must return an object or undefined.

Description​

The handler.getOwnPropertyDescriptor() method is a trap for Object.getOwnPropertyDescriptor().

Interceptions​

This trap can intercept these operations:

Or any other operation that invokes the [[GetOwnProperty]] internal method.

Invariants​

If the following invariants are violated, the trap throws a TypeError when invoked.

  • getOwnPropertyDescriptor() must return an object or undefined.
  • A property cannot be reported as non-existent, if it exists as a non-configurable own property of the target object.
  • A property cannot be reported as non-existent, if it exists as an own property of the target object and the target object is not extensible.
  • A property cannot be reported as existent, if it does not exists as an own property of the target object and the target object is not extensible.
  • A property cannot be reported as non-configurable, if it does not exists as an own property of the target object or if it exists as a configurable own property of the target object.
  • The result of Object.getOwnPropertyDescriptor(target) can be applied to the target object using Object.defineProperty() and will not throw an exception.