Using Calculate Formula Reactively

[BrianHung]

Is there a way to use calculateFormula reactively?

For example, I want to build a selection summary that applies a formula like SUM across all cells in a selection range. I can convert that selection range to use A1 notation, e.g. =SUM(A1:D10).

But am wondering how to update that result whenever any value within A1:D10 changes. In this context, I sort of want the normal reactivity as if =SUM(Grid1!A1:D10) was a cell but not have hack it into a sheet.

The ideal DX I'm looking for is something like this so I can agnostically integrate it into React.

const unsubscribe = subscribe(`=SUM(Grid1!A1:D10)`, newValue => console.log(newValue));

I have tried looking at handsontable's ColumnSummary plugin as inspiration, and it feels close?

Just need a utility function to parse a generic formula for all of its cell dependents, then check if changes from the valuesUpdated listener intersect the dependents.

[AMBudnik]

Hi @BrianHung, thanks for reaching out!

I think the best approach to this problem would be to define a named expression and use the valuesUpdated event to listen for changes in the named expression value.

demo: https://stackblitz.com/edit/js-4kvpek?file=index.html,index.js

[BrianHung]

Oh! I didn't know that valuesUpdated contained changes for namedExpression. Works perfectly for this use case.

[AMBudnik]

I'm more than happy to hear that it meets your requirements.