Struct nodex_api::value::Function

source · [−]
pub struct Function<F>(_, _);

Implementations

This API allows an add-on author to create a function object in native code. This is the primary mechanism to allow calling into the add-on’s native code from JavaScript. The newly created function is not automatically visible from script after this call. Instead, a property must be explicitly set on any object that is visible to JavaScript, in order for the function to be accessible from script. In order to expose a function as part of the add-on’s module exports, set the newly created function on the exports object. A sample module might look as follows:

napi_value SayHello(napi_env env, napi_callback_info info) {
 printf("Hello\n");
 return NULL;
}

napi_value Init(napi_env env, napi_value exports) {
 napi_status status;
 napi_value fn;
 status = napi_create_function(env, NULL, 0, SayHello, NULL, &fn);
 if (status != napi_ok) return NULL;
 status = napi_set_named_property(env, exports, "sayHello", fn);
 if (status != napi_ok) return NULL;
 return exports;
}

NAPI_MODULE(NODE_GYP_MODULE_NAME, Init)

Given the above code, the add-on can be used from JavaScript as follows:

const myaddon = require('./addon');
myaddon.sayHello();

The string passed to require() is the name of the target in binding.gyp responsible for creating the .node file.

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

JavaScript Functions are described in Section 19.2 of the ECMAScript Language Specification.

This method allows a JavaScript function object to be called from a native add-on. This is the primary mechanism of calling back from the add-on’s native code into JavaScript. For the special case of calling into JavaScript after an async operation, see napi_make_callback.

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

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

construct value from raw pointer

inner value

napi_value type cast

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

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. Read more

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

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. Read more

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

This API represents invoking the IsArray operation on the object as defined in Section 7.2.2 of the ECMAScript Language Specification. Read more

This API checks if the Object passed in is an array buffer.

This API checks if the Object passed in is a buffer.

This API checks if the Object passed in is a error.

This API checks if the Object passed in is a typed array.

This API checks if the Object passed in is a DataView.

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

Returns napi_ok if the API succeeded. Read more

the NapiEnv of current value

the raw-handle of current value

get null singleton

get undefined singleton

get global singleton

value is throwable

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). Read more

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. Read more

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

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

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. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Performs the conversion.

Performs the conversion.

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into)

Uses borrowed data to replace owned data, usually by cloning. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.