Set null legend values per series?

Hi, is there any way to set a custom null legend value for a series? If the mouse is not hovering over the chart, the legend shows -- which, as far as I can tell, is hard coded here:

https://github.com/leeoniya/uPlot/blob/d12f84b9daf770ea9b04d42e04ee9738ca055024/src/uPlot.js#L556

I would like the legend to show a different default value that is different per series. In my case for example I would like to render the sum of all data for a series. I can calculate the value myself of course, I’m just not sure how to render it in place of the -- while keeping the mouse over live legend functionality.

Thank you very much!

[leeoniya]

ah, ok.

i’ll see about adding something that invokes series.value() with a null idx during data updates and cursor hiding events.

[mxlje]

Thank you for your quick reply. I tried that and as far as I can tell it only is called when actually hovering, not for the case where the user is not hovering, which is the “null legend” case I tried to describe. Maybe my question wasn’t clear though so I’ll try to rephrase:

When the mouse is not over the chart, the value in the legend for every series is shown as -- (see screenshot below). Returning a value from the value: function does influence the legend, but only when hovering over a specific x point. The hovering already works fine without customization though.

What I would want is a function on the series that gets all data points for the currently visible part of the x axis (which can change when the user zooms in) and whatever it returns is rendered in the legend when the user is not hovering the chart, replacing the --. In this specific case I would use it to sum the value of all points.

Thank you again.