Typescript readonly data array is incompatible with data property interface definition

[mward-sudo]

The Problem

I'm attempting to use a functional programming style to the extent it is possible to do so using the JavaScript frameworks I am using.

As part of this effort, I am defining my arguments and data constructs as readonly using TypeScript so that my data is not mutable.

However, I am experiencing an issue with Victory in that the TypeScript interface for the data property (on the VictoryLine component for example) cannot accept a readonly value because its typescript definition is using the mutable any type.

I get the following error:

The type 'ChartData' is 'readonly' and cannot be assigned to the mutable type 'any[]'.

Reproduction

https://codesandbox.io/s/winter-tree-00wu4z?file=/index.tsx

Potential Solution

In limited testing I tried changing the definition for the data property from any[] to any[] | readonly any[] and this solved the TypeScript error, but I haven't tested this properly.

If this issue is accepted, and the above is deemed an acceptable solution, then I will create a PR that modifies the TypeScript interfaces in the correct places.

[becca-bailey]

Thanks for reporting this issue! We have been working on a Typescript conversion on our end, and there might be some kinks to work out with some of the typings. FYI @scottrippey.

[scottrippey]

I see no issue with marking data as readonly, since we never mutate it. PR #2313