使用go和Otto调用JavaScript回调函数

Question

How can I use Otto to call javascript functions passed as a parameter (as a callback function)?

Example javascript:

test.testCallback(function(a) { console.log(a) });

Example go code using Otto:

func main() {
    motto.AddModule("test", testModuleLoader)
    vm := motto.New()
    vm.Run("test.js")
}

func testModuleLoader(vm *motto.Motto) (otto.Value, error) {
    test, _ := vm.Object(`({})`)
    test.Set("testCallback", func(call otto.FunctionCall) otto.Value {
        fn := call.Argument(0)
        // HOW TO CALL fn("value for a") ?
        return fn
    })

    return vm.ToValue(test)
}

Answer 1

Yes, this is possible, although at this point I've only done it with callbacks wrapped in an object. So your code would look like this:

func main() {
    motto.AddModule("test", testModuleLoader)
    vm := motto.New()
    vm.Run("test.js")
}

func testModuleLoader(vm *motto.Motto) (otto.Value, error) {
    test, _ := vm.Object(`({})`)
    test.Set("testCallback", func(call otto.FunctionCall) otto.Value {
        fnWrapper := call.Argument(0).Object()

        // HOW TO CALL fn("value for a") ?
        cb, _ := fnWrapper.Get("cb")
        if cb.IsFunction() {
          cbArgs := "value for a"
          return fnWrapper.Call("cb", cbArgs) // cbArgs is optional
        }

        return motto.NullValue()
    })

    return vm.ToValue(test)
}