Function registerFactoryAsConstructor

plugins/jsvm/binds.go:1098–1134

registerFactoryAsConstructor registers the factory function as native JS constructor. If there is missing or nil arguments, their type zero value is used.

(vm *goja.Runtime, constructorName string, factoryFunc any)

//
// If there is missing or nil arguments, their type zero value is used.
func registerFactoryAsConstructor(vm *goja.Runtime, constructorName string, factoryFunc any) {
	rv := reflect.ValueOf(factoryFunc)
	rt := cachedFactoryFuncTypes.GetOrSet(constructorName, func() reflect.Type {
		return reflect.TypeOf(factoryFunc)
	})
	totalArgs := rt.NumIn()

	vm.Set(constructorName, func(call goja.ConstructorCall) *goja.Object {
		args := make([]reflect.Value, totalArgs)

		for i := 0; i < totalArgs; i++ {
			v := call.Argument(i).Export()

			// use the arg type zero value
			if v == nil {
				args[i] = reflect.New(rt.In(i)).Elem()
			} else if number, ok := v.(int64); ok {
				// goja uses int64 for "int"-like numbers but we rarely do that and use int most of the times
				// (at later stage we can use reflection on the arguments to validate the types in case this is not sufficient anymore)
				args[i] = reflect.ValueOf(int(number))
			} else {
				args[i] = reflect.ValueOf(v)
			}
		}

		result := rv.Call(args)

		if len(result) != 1 {
			panic("the factory function should return only 1 item")
		}

		value := vm.ToValue(result[0].Interface()).(*goja.Object)
		value.SetPrototype(call.This.Prototype())

		return value
	})
}

// structConstructor wraps the provided struct with a native JS constructor.
//