+ void SetWeak(P *parameter,
+ typename WeakCallbackInfo::Callback callback,
+ WeakCallbackType type);
+
+ void ClearWeak();
+
+ /**
+ * Marks the reference to this object independent. Garbage collector is free
+ * to ignore any object groups containing this object. Weak callback for an
+ * independent handle should not assume that it will be preceded by a global
+ * GC prologue callback or followed by a global GC epilogue callback.
+ */
+ void MarkIndependent() const;
+
+ bool IsIndependent() const;
+
+ /** Checks if the handle holds the only reference to an object. */
+ bool IsNearDeath() const;
+
+ /** Returns true if the handle's reference is weak. */
+ bool IsWeak() const
+};
+```
+
+See the V8 documentation for [`PersistentBase`](https://v8docs.nodesource.com/node-8.11/d4/dca/classv8_1_1_persistent_base.html) for further information.
+
+**Tip:** To get a `v8::Local` reference to the original object back from a `PersistentBase` or `Persistent` object:
+
+```c++
+v8::Local object = Nan::New(persistent);
+```
+
+
+### Nan::NonCopyablePersistentTraits & v8::NonCopyablePersistentTraits
+
+Default traits for `Nan::Persistent`. This class does not allow use of the a copy constructor or assignment operator. At present `kResetInDestructor` is not set, but that will change in a future version.
+
+Definition:
+
+_(note: this is implemented as `Nan::NonCopyablePersistentTraits` for older versions of V8 and the native `v8::NonCopyablePersistentTraits` is used for newer versions of V8)_
+
+```c++
+template class NonCopyablePersistentTraits {
+ public:
+ typedef Persistent > NonCopyablePersistent;
+
+ static const bool kResetInDestructor = false;
+
+ template
+ static void Copy(const Persistent &source,
+ NonCopyablePersistent *dest);
+
+ template static void Uncompilable();
+};
+```
+
+See the V8 documentation for [`NonCopyablePersistentTraits`](https://v8docs.nodesource.com/node-8.11/de/d73/classv8_1_1_non_copyable_persistent_traits.html) for further information.
+
+
+### Nan::CopyablePersistentTraits & v8::CopyablePersistentTraits
+
+A helper class of traits to allow copying and assignment of `Persistent`. This will clone the contents of storage cell, but not any of the flags, etc..
+
+Definition:
+
+_(note: this is implemented as `Nan::CopyablePersistentTraits` for older versions of V8 and the native `v8::NonCopyablePersistentTraits` is used for newer versions of V8)_
+
+```c++
+template
+class CopyablePersistentTraits {
+ public:
+ typedef Persistent > CopyablePersistent;
+
+ static const bool kResetInDestructor = true;
+
+ template
+ static void Copy(const Persistent &source,
+ CopyablePersistent *dest);
+};
+```
+
+See the V8 documentation for [`CopyablePersistentTraits`](https://v8docs.nodesource.com/node-8.11/da/d5c/structv8_1_1_copyable_persistent_traits.html) for further information.
+
+
+### Nan::Persistent
+
+A type of `PersistentBase` which allows copy and assignment. Copy, assignment and destructor behavior is controlled by the traits class `M`.
+
+Definition:
+
+```c++
+template >
+class Persistent;
+
+template class Persistent : public PersistentBase {
+ public:
+ /**
+ * A Persistent with no storage cell.
+ */
+ Persistent();
+
+ /**
+ * Construct a Persistent from a v8::Local. When the v8::Local is non-empty, a
+ * new storage cell is created pointing to the same object, and no flags are
+ * set.
+ */
+ template Persistent(v8::Local that);
+
+ /**
+ * Construct a Persistent from a Persistent. When the Persistent is non-empty,
+ * a new storage cell is created pointing to the same object, and no flags are
+ * set.
+ */
+ Persistent(const Persistent &that);
+
+ /**
+ * The copy constructors and assignment operator create a Persistent exactly
+ * as the Persistent constructor, but the Copy function from the traits class
+ * is called, allowing the setting of flags based on the copied Persistent.
+ */
+ Persistent &operator=(const Persistent &that);
+
+ template
+ Persistent &operator=(const Persistent &that);
+
+ /**
+ * The destructor will dispose the Persistent based on the kResetInDestructor
+ * flags in the traits class. Since not calling dispose can result in a
+ * memory leak, it is recommended to always set this flag.
+ */
+ ~Persistent();
+};
+```
+
+See the V8 documentation for [`Persistent`](https://v8docs.nodesource.com/node-8.11/d2/d78/classv8_1_1_persistent.html) for further information.
+
+
+### Nan::Global
+
+A type of `PersistentBase` which has move semantics.
+
+```c++
+template class Global : public PersistentBase {
+ public:
+ /**
+ * A Global with no storage cell.
+ */
+ Global();
+
+ /**
+ * Construct a Global from a v8::Local. When the v8::Local is non-empty, a new
+ * storage cell is created pointing to the same object, and no flags are set.
+ */
+ template Global(v8::Local that);
+ /**
+ * Construct a Global from a PersistentBase. When the Persistent is non-empty,
+ * a new storage cell is created pointing to the same object, and no flags are
+ * set.
+ */
+ template Global(const PersistentBase &that);
+
+ /**
+ * Pass allows returning globals from functions, etc.
+ */
+ Global Pass();
+};
+```
+
+See the V8 documentation for [`Global`](https://v8docs.nodesource.com/node-8.11/d5/d40/classv8_1_1_global.html) for further information.
+
+
+### Nan::WeakCallbackInfo
+
+`Nan::WeakCallbackInfo` is used as an argument when setting a persistent reference as weak. You may need to free any external resources attached to the object. It is a mirror of `v8:WeakCallbackInfo` as found in newer versions of V8.
+
+Definition:
+
+```c++
+template class WeakCallbackInfo {
+ public:
+ typedef void (*Callback)(const WeakCallbackInfo& data);
+
+ v8::Isolate *GetIsolate() const;
+
+ /**
+ * Get the parameter that was associated with the weak handle.
+ */
+ T *GetParameter() const;
+
+ /**
+ * Get pointer from internal field, index can be 0 or 1.
+ */
+ void *GetInternalField(int index) const;
+};
+```
+
+Example usage:
+
+```c++
+void weakCallback(const WeakCallbackInfo &data) {
+ int *parameter = data.GetParameter();
+ delete parameter;
+}
+
+Persistent obj;
+int *data = new int(0);
+obj.SetWeak(data, callback, WeakCallbackType::kParameter);
+```
+
+See the V8 documentation for [`WeakCallbackInfo`](https://v8docs.nodesource.com/node-8.11/d8/d06/classv8_1_1_weak_callback_info.html) for further information.
+
+
+### Nan::WeakCallbackType
+
+Represents the type of a weak callback.
+A weak callback of type `kParameter` makes the supplied parameter to `Nan::PersistentBase::SetWeak` available through `WeakCallbackInfo::GetParameter`.
+A weak callback of type `kInternalFields` uses up to two internal fields at indices 0 and 1 on the `Nan::PersistentBase` being made weak.
+Note that only `v8::Object`s and derivatives can have internal fields.
+
+Definition:
+
+```c++
+enum class WeakCallbackType { kParameter, kInternalFields };
+```