My Google-Fu is failing me...

We have a visualization plugin that can also serve as an editor to modify the data it is visualizing.  What is the best way to save the data from the visualizer back to Galaxy?

I seem to recall reading (somewhere, sometime) that the REST API could not do this and the "best" solution is to invoke the upload tool to upload data into the current history.  I have used the upload tool from the Python and Blend4J APIs, but I can not find a JavaScript example for invoking the upload tool.

So two questions:

1. Is the upload tool (still) the recommended way to put data into the current history via API calls?

2. How do I invoke the upload tool from JavaScript?

Thanks,

Keith