如何从JSFunction返回JSObject？

Question

我想从FFI函数定义中返回对Javascript对象的引用，以便稍后能够操作该对象：

import           Data.Aeson
import           Foreign.JavaScript (JSObject, NewJSObject, unsafeCreateJSObject)
import           Foreign.RemotePtr (RemotePtr)
import           Graphics.UI.Threepenny.Core hiding (text)

mkJSObject :: JSFunction NewJSObject -> UI JSObject
mkJSObject f = askWindow >>= liftIO . flip unsafeCreateJSObject f

polyLine :: [[Double]] -> Value -> UI JSObject
polyLine points = mkJSObject . f points
  where
    f :: [[Double]] -> Value -> JSFunction NewJSObject
    f = ffi "L.polyline(%1, %2).addTo(map)"

但是底层的Javascript窗口似乎不能公开访问。有没有其他方法可以创建对Javascript对象的引用？

Answer 1

实际上要简单得多:只需从JSFunction返回一个JSObject，它就会被正确编组：

polyLine :: [[Double]] -> Value -> UI JSObject
polyLine points = callFunction . f points
  where
    f :: [[Double]] -> Value -> JSFunction JSObject
    f = ffi "L.polyline(%1, %2).addTo(map)"