Raw jsi::Value / jsi::Runtime

Even though Nitro supports virually any type in JS, there are certain use-cases where you might want to use a jsi::Value or jsi::Runtime directly - and Nitro provides an escape hatch for this.

Since JSI is not typed, Nitrogen does not have typing support for a method that takes raw jsi::Values - so you have to define it yourself by overriding loadHybridMethods() in C++:

class HybridMath : public HybridMathSpec {
public:
  HybridMath(): HybridObject(TAG) {}

public:
  jsi::Value myRawMethod(jsi::Runtime& runtime,
                         const jsi::Value& thisValue,
                         const jsi::Value* args,
                         size_t count);

public:
  void loadHybridMethods() override;
}

warning

In JS, myRawMethod is not typed. You are expected to provide type-safety for it by safely checking the arguments and return values yourself.

The implementation of your loadHybridMethods() should call the base's loadHybridMethods(), and then register your raw JSI methods:

void HybridMath::loadHybridMethods() {
  // 1. Load base methods
  HybridMathSpec::loadHybridMethods();
  // 2. Register own methods
  registerHybrids(this, [](Prototype& prototype) {
    prototype.registerRawHybridMethod("myRawMethod",
                                      /* args count */ 2,
                                      &HybridMath::myRawMethod);
  });
}

important

If you don't have a base spec (here, HybridMathSpec is a nitrogenerated spec), you just want to call HybridObject::loadHybridMethods().

And lastly, implement your raw JSI method:

jsi::Value HybridMath::myRawMethod(jsi::Runtime& runtime,
                                   const jsi::Value& thisValue,
                                   const jsi::Value* args,
                                   size_t count) {
  double a = args[0].asNumber();
  double b = args[1].asNumber();
  return jsi::Value(a + b);
}

note

The syntax of a raw JSI method is always the same as the one of a jsi::HostFunctionType.

tip

You can use Nitro's converters by including #include <NitroModules/JSIConverter.hpp>, then using it:

double a = JSIConverter<double>::fromJSI(runtime, args[0]);