_.js

var domtoimage = window.domtoimage;

exports.toSvgImpl = function (element) {
    return function () {
        console.log("toSvgImpl");
        return domtoimage.toSvg(element);
    };
};

exports.toBlobImpl = function (element) {
    return function () {
        return domtoimage.toBlob(element);
    };
};

exports.toJpegImpl = function (element) {
    return function () {
        return domtoimage.toJpeg(element);
    };
};

exports.toPngImpl = function (element) {
    return function () {
        return domtoimage.toPng(element);
    };
};

exports.toPixelDataImpl = function (element) {
    return function () {
        return domtoimage.toPixelData(element);
    };
};

exports.promiseCallbacks = function (promiseEff) {
    return function (error) {
        return function (success) {
            return function () {
                promiseEff()
                    .then(function (x) { success(x)(); }, function (x) { error(x)(); });
            };
        };
    };
};

_.purs

module DomToImage where

import Prelude

import Control.Monad.Aff (Aff)
import Control.Monad.Aff as Aff
import Control.Monad.Eff (Eff, kind Effect)
import Control.Monad.Eff.Exception (Error)
import Data.ArrayBuffer.Types (Uint8Array)
import DOM.File.Types (Blob)
import DOM.Node.Types (Element)

newtype DataUri = DataUri String

unDataUri :: DataUri -> String
unDataUri (DataUri s) = s

foreign import data DOMTOIMAGE :: Effect

foreign import data Promise :: Type -> Type

foreign import promiseCallbacks
  :: forall a b
  . Eff a (Promise b)
  -> (Error -> Eff a Unit)
  -> (b -> Eff a Unit)
  -> Eff a Unit

foreign import toBlobImpl
  :: forall a
  . Element
  -> Eff (domToImage :: DOMTOIMAGE | a) (Promise Blob)

foreign import toSvgImpl
  :: forall a
  . Element
  -> Eff (domToImage :: DOMTOIMAGE | a) (Promise DataUri)

foreign import toJpegImpl
  :: forall a
  . Element
  -> Eff (domToImage :: DOMTOIMAGE | a) (Promise DataUri)

foreign import toPngImpl
  :: forall a
  . Element
  -> Eff (domToImage :: DOMTOIMAGE | a) (Promise DataUri)

foreign import toPixelDataImpl
  :: forall a
  . Element
  -> Eff (domToImage :: DOMTOIMAGE | a) (Promise Uint8Array)

toBlob :: forall a. Element -> Aff (domToImage :: DOMTOIMAGE | a) Blob
toBlob = Aff.makeAff <<< promiseCallbacks <<< toBlobImpl

toSvg :: forall a. Element -> Aff (domToImage :: DOMTOIMAGE | a) DataUri
toSvg = Aff.makeAff <<< promiseCallbacks <<< toSvgImpl

toPng :: forall a. Element -> Aff (domToImage :: DOMTOIMAGE | a) DataUri
toPng = Aff.makeAff <<< promiseCallbacks <<< toPngImpl

toPixelData :: forall a. Element -> Aff (domToImage :: DOMTOIMAGE | a) Uint8Array
toPixelData = Aff.makeAff <<< promiseCallbacks <<< toPixelDataImpl

toJpeg :: forall a. Element -> Aff (domToImage :: DOMTOIMAGE | a) DataUri
toJpeg = Aff.makeAff <<< promiseCallbacks <<< toJpegImpl