the Javascript Scatter Plot node seems to ignore size information from the Size Manager (while it works well with the colors assigned by the Color Manager). Is there a way to teach the JS Scatter Plot displaying different sizes per item?
unfortunately the Javascript Scatter Plot node is not size-aware, it only considers colors as you already found out. An additional Javascript Bubble Chart node would be in order.
Did you consider using the Bubble Chart node from JFreeChart instead? In it you can configure one of your data columns as determining the radius of each bubble.
Or if you want to stick to a Javascript view, you can always use the Generic Javascript View node and plot a bubble chart with D3.js or Plotly.js. Regarding the latter, I wrote some time ago a tutorial explaining how include and use it:
I tried and the JS scatterplot just accept the color manager and ignores Size and Shapes. It would be nice that you could apply shapes, color and sizes.
Please add another +1 from me. With all the new Plotly integration (in which it does not work either) and shift to WebPortal Views + interactivity features I think this would be a very important addition. Maybe meanwhile add a warning that Size properties are unused. I spent some time playing with different scaling options since I thought this would be the culprit.