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Diffstat (limited to 'doc/api')
-rw-r--r-- | doc/api/n-api.md | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/doc/api/n-api.md b/doc/api/n-api.md index f877b6e6d63..7852454a929 100644 --- a/doc/api/n-api.md +++ b/doc/api/n-api.md @@ -3022,6 +3022,29 @@ constructor and methods can be called from JavaScript. callback, [`napi_unwrap`][] obtains the C++ instance that is the target of the call. +For wrapped objects it may be difficult to distinguish between a function +called on a class prototype and a function called on an instance of a class. +A common pattern used to address this problem is to save a persistent +reference to the class constructor for later `instanceof` checks. + +As an example: + +```C +napi_value MyClass_constructor = nullptr; +status = napi_get_reference_value(env, MyClass::es_constructor, &MyClass_constructor); +assert(napi_ok == status); +bool is_instance = false; +status = napi_instanceof(env, es_this, MyClass_constructor, &is_instance); +assert(napi_ok == status); +if (is_instance) { + // napi_unwrap() ... +} else { + // otherwise... +} +``` + +The reference must be freed once it is no longer needed. + ### *napi_define_class* <!-- YAML added: v8.0.0 |