Jsonify makes Record<string, any> disappear

[kentcdodds]

Here's a TS Playground:

import type { Jsonify } from "type-fest";

type Data = Jsonify<{
  payload: Record<string, any>;
}>;

declare const d: Data;
console.log(d.payload) // <-- Property 'payload' does not exist on type 'JsonifyObject<{}>'.

This feels like a bug to me. It's causing an issue for me in the upcoming version of Remix: remix-run/remix#7246

My current workaround is to change the type to unknown instead of any (edmundhung/conform#272 which will hopefully be merged soon). I think is the proper thing to do, but sometimes that's hard because you may not control the type. I think it's more correct to keep the record around on the type.

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[kentcdodds]

Behavior confirmed via #668 PR workflow run: https://github.com/sindresorhus/type-fest/actions/runs/5959009025/job/16164096431?pr=668#step:5:11

  ✖  331:43  Argument of type JsonifyObject<{}> is not assignable to parameter of type { payload: Record<string, any>; }.
  Property payload is missing in type JsonifyObject<{}> but required in type { payload: Record<string, any>; }.  

[sindresorhus]

I agree. Record<string, any> is already passed through when it's top-level, and it makes sense to also do it when it's a property.

[MichaelDeBoey]

Same issue happens when having Record<string, string> or Record<string, Date>

CC/ @sachinraja as he created the original JsonifyObject generic in #519, so maybe he has an idea of where the problem would be?

[sachinraja]

I’ll take a look when I can but that type actually comes from Remix's initial jsonify implementation

[MichaelDeBoey]

@sachinraja Is there anything I can help you with to get this one fixed?

[pcattori]

Tried reproducing this. At first, looks like the issue is resolved since there aren't red squigglies, but then I noticed that payload gets inferred as a number 🤷

https://tsplay.dev/mZJO1m

I'm looking into this now

[pcattori]

Ok tracked this down to this line:

T extends TypedArray ? Record<string, number> :
// ...

That extends TypedArray check triggers for Record<string, any>. Similar to how IsAny is checked at the beginning of Jsonify, we need to check for Record<string, any> before any other extends Record<string, _> checks (which TypedArray implicitly is).

Here's a minimal repro with suggested fix: https://tsplay.dev/N7VJqw