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Version: 3.13.0

Object.isExtensible()

The Object.isExtensible() method determines if an object is extensible (whether it can have new properties added to it).

Syntax​

Object.isExtensible(obj)

Parameters​

  • obj
    • : The object which should be checked.

Return value​

A Boolean indicating whether or not the given object is extensible.

Description​

Objects are extensible by default: they can have new properties added to them, and their [[Prototype]] can be re-assigned. An object can be marked as non-extensible using one of Object.preventExtensions(), Object.seal(), Object.freeze(), or Reflect.preventExtensions().