Struct JsClass

pub struct JsClass(/* private fields */);

Implementations

impl JsClass

pub fn new<F, P, T, R>( env: NapiEnv, name: impl AsRef<str>, func: F, properties: P, ) -> NapiResult<JsClass>

where T: FromJsArgs, R: NapiValueT, F: FnMut(JsObject, T) -> NapiResult<R>, P: AsRef<[NapiPropertyDescriptor]>,

Defines a JavaScript class, including:

• A JavaScript constructor function that has the class name. When wrapping a corresponding C++ class, the callback passed via constructor can be used to instantiate a new C++ class instance, which can then be placed inside the JavaScript object instance being constructed using napi_wrap.
• Properties on the constructor function whose implementation can call corresponding static data properties, accessors, and methods of the C++ class (defined by property descriptors with the napi_static attribute).
• Properties on the constructor function’s prototype object. When wrapping a C++ class, non-static data properties, accessors, and methods of the C++ class can be called from the static functions given in the property descriptors without the napi_static attribute after retrieving the C++ class instance placed inside the JavaScript object instance by using napi_unwrap.

When wrapping a C++ class, the C++ constructor callback passed via constructor should be a static method on the class that calls the actual class constructor, then wraps the new C++ instance in a JavaScript object, and returns the wrapper object. See napi_wrap for details.

The JavaScript constructor function returned from napi_define_class is often saved and used later to construct new instances of the class from native code, and/or to check whether provided values are instances of the class. In that case, to prevent the function value from being garbage-collected, a strong persistent reference to it can be created using napi_create_reference, ensuring that the reference count is kept >= 1.

Any non-NULL data which is passed to this API via the data parameter or via the data field of the napi_property_descriptor array items can be associated with the resulting JavaScript constructor (which is returned in the result parameter) and freed whenever the class is garbage-collected by passing both the JavaScript function and the data to napi_add_finalizer.

pub fn new_instance<T>(&self, args: T) -> NapiResult<JsObject>

where T: ToJsArgs,

This method is used to instantiate a new JavaScript value using a given napi_value that represents the constructor for the object.

Trait Implementations

impl Clone for JsClass

fn clone(&self) -> JsClass

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for JsClass

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl NapiValueCheck for JsClass

fn check(&self) -> NapiResult<bool>

impl NapiValueT for JsClass

fn from_raw(env: NapiEnv, raw: napi_value) -> JsClass

construct value from raw pointer

fn value(&self) -> JsValue

inner value

unsafe fn cast<T: NapiValueT>(&self) -> T

napi_value type cast

fn cast_checked<T: NapiValueT>(&self) -> NapiResult<T>

Upcast to specified value

fn kind(&self) -> NapiResult<NapiValuetype>

Returns napi_ok if the API succeeded.

fn coerce_to_bool(&self) -> NapiResult<JsBoolean>

This API implements the abstract operation ToBoolean() as defined in Section 7.1.2 of the ECMAScript Language Specification.

fn coerce_coerce_to_number(&self) -> NapiResult<JsNumber>

This API implements the abstract operation ToNumber() as defined in Section 7.1.3 of the ECMAScript Language Specification. This function potentially runs JS code if the passed-in value is an object.

fn coerce_to_object(&self) -> NapiResult<JsObject>

This API implements the abstract operation ToObject() as defined in Section 7.1.13 of the ECMAScript Language Specification.

fn coerce_to_string(&self) -> NapiResult<JsString>

This API implements the abstract operation ToString() as defined in Section 7.1.13 of the ECMAScript Language Specification. This function potentially runs JS code if the passed-in value is an object.

fn instance_of(&self, constructor: JsFunction) -> NapiResult<bool>

This API represents invoking the instanceof Operator on the object as defined in Section 12.10.4 of the ECMAScript Language Specification.

fn equals(&self, rhs: impl NapiValueT) -> NapiResult<bool>

This API represents the invocation of the Strict Equality algorithm as defined in Section 7.2.14 of the ECMAScript Language Specification.

fn env(&self) -> NapiEnv

the NapiEnv of current value

fn raw(&self) -> napi_value

the raw-handle of current value

fn null(&self) -> NapiResult<JsNull>

get null singleton

fn undefined(&self) -> NapiResult<JsUndefined>

get undefined singleton

fn global(&self) -> NapiResult<JsGlobal>

get global singleton

fn throw(&self) -> NapiResult<()>

value is throwable

fn define_properties<P>(&self, properties: P) -> NapiResult<()>

where P: AsRef<[NapiPropertyDescriptor]>,

This method allows the efficient definition of multiple properties on a given object. The properties are defined using property descriptors (see napi_property_descriptor). Given an array of such property descriptors, this API will set the properties on the object one at a time, as defined by DefineOwnProperty() (described in Section 9.1.6 of the ECMA-262 specification).

fn gc<Finalizer>(&mut self, finalizer: Finalizer) -> NapiResult<NapiRef>

where Finalizer: FnOnce(NapiEnv) -> NapiResult<()>,

This is a hook which is fired when the value is gabage-collected. For napi >= 5, we use napi_add_finalizer, For napi < 5, we use napi_wrap.

fn finalizer<Finalizer>(&self, finalizer: Finalizer) -> NapiResult<NapiRef>

where Finalizer: FnOnce(NapiEnv) -> NapiResult<()>,

Adds a napi_finalize callback which will be called when the JavaScript object in js_object is ready for garbage collection. This API is similar to napi_wrap() except that:

fn wrap<T>( &mut self, data: T, finalizer: impl FnOnce(NapiEnv, T) -> NapiResult<()>, ) -> NapiResult<NapiRef>

Wraps a native instance in a JavaScript object. The native instance can be retrieved later using napi_unwrap().

fn unwrap<T>(&self) -> NapiResult<Option<&mut T>>

Retrieves a native instance that was previously wrapped in a JavaScript object using napi_wrap().

fn remove_wrap<T>(&mut self) -> NapiResult<T>

Retrieves a native instance that was previously wrapped in the JavaScript object js_object using napi_wrap() and removes the wrapping. If a finalize callback was associated with the wrapping, it will no longer be called when the JavaScript object becomes garbage-collected.

fn type_tag_object(&self, tag: &NapiTypeTag) -> NapiResult<()>

Associates the value of the type_tag pointer with the JavaScript object. napi_check_object_type_tag() can then be used to compare the tag that was attached to the object with one owned by the addon to ensure that the object has the right type. If the object already has an associated type tag, this API will return napi_invalid_arg.

fn check_object_type_tag(&self, tag: &NapiTypeTag) -> NapiResult<bool>

Compares the pointer given as type_tag with any that can be found on js_object. If no tag is found on js_object or, if a tag is found but it does not match type_tag, then result is set to false. If a tag is found and it matches type_tag, then result is set to true.

impl Copy for JsClass