how to get a resolve value in a promise?

[czz362100]

hey team, i have some confusions in these code

vm := goja.New()
	promise, err := vm.RunString(`
			async function sum(a, b) {
    			return a+b;
			}
	`)
	if err != nil {
		panic(err)
	}
	add, ok := goja.AssertFunction(vm.Get("sum"))
	if !ok {
		panic("not a function")
	}

	value, _ := add(goja.Undefined(), vm.ToValue(40), vm.ToValue(2))
	return value

in this example, the sum Function return a [object, Promise], but i want to get a Resolved value, please tell me how do i?

[shiroyk]

Export to promise

func main() {
	vm := goja.New()
	_, err := vm.RunString(`
			async function sum(a, b) {
    			return a+b;
			}
	`)
	if err != nil {
		panic(err)
	}
	add, ok := goja.AssertFunction(vm.Get("sum"))
	if !ok {
		panic("not a function")
	}

	value, _ := add(goja.Undefined(), vm.ToValue(40), vm.ToValue(2))

	var result any
	if p, ok := value.Export().(*goja.Promise); ok {
		switch p.State() {
		case goja.PromiseStateRejected:
			panic(p.Result().String())
		case goja.PromiseStateFulfilled:
			result = p.Result().Export()
		default:
			panic("unexpected promise state pending")
		}
	}

	fmt.Println(result)
}

[72wo]

Export to promise

func main() {
	vm := goja.New()
	_, err := vm.RunString(`
			async function sum(a, b) {
    			return a+b;
			}
	`)
	if err != nil {
		panic(err)
	}
	add, ok := goja.AssertFunction(vm.Get("sum"))
	if !ok {
		panic("not a function")
	}

	value, _ := add(goja.Undefined(), vm.ToValue(40), vm.ToValue(2))

	var result any
	if p, ok := value.Export().(*goja.Promise); ok {
		switch p.State() {
		case goja.PromiseStateRejected:
			panic(p.Result().String())
		case goja.PromiseStateFulfilled:
			result = p.Result().Export()
		default:
			panic("unexpected promise state pending")
		}
	}

	fmt.Println(result)
}

I would like to ask a question，the promise is async，so in goja in golang it is sync？If the execution is not completed when the results are obtained，it is true？

[shiroyk]

Export to promise

func main() {
	vm := goja.New()
	_, err := vm.RunString(`
			async function sum(a, b) {
    			return a+b;
			}
	`)
	if err != nil {
		panic(err)
	}
	add, ok := goja.AssertFunction(vm.Get("sum"))
	if !ok {
		panic("not a function")
	}

	value, _ := add(goja.Undefined(), vm.ToValue(40), vm.ToValue(2))

	var result any
	if p, ok := value.Export().(*goja.Promise); ok {
		switch p.State() {
		case goja.PromiseStateRejected:
			panic(p.Result().String())
		case goja.PromiseStateFulfilled:
			result = p.Result().Export()
		default:
			panic("unexpected promise state pending")
		}
	}

	fmt.Println(result)
}

I would like to ask a question，the promise is async，so in goja in golang it is sync？If the execution is not completed when the results are obtained，it is true？

It's async, you can also see https://github.com/dop251/goja/blob/28ee0ee714f3e8218c14e2cd2d7a67ec94848c21/builtin_promise.go#L592-L611