TanStack / TanStack/store

`shallow` doesn't correctly compare different object instances if they only have property getters

Open
#218 0 comments 2 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Dominant language
TypeScript
Stars
893
Forks
114
Avg merge
8d 14h
Merged PRs (30d)
3

Description

Describe the bug

I'm using @tanstack/react-form, but traced the issue back to the store here. Specifically, I'm trying to store Temporal.Duration values, but store updates are not being received via useStore because shallow returns true when both objects have no keys, i.e. Object.keys(objA) return [], instead of comparing referential equality at that point.

Steps to Reproduce the Bug or Issue

This, and any object factory that use getters instead of static properties return true.

shallow(Temporal.Duration.from({ hours: 1 }), Temporal.Duration.from({ days: 2 }));
Expected behavior

Expect to see false, since they are different values, different objects.

Screenshots or Videos

No response

Platform
  • OS: macOS
  • Browser: Arc (Chromium)
  • Version: 138.0
Additional context

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating the store's shallow implementation and its existing tests. Reproduce the reported comparison with two distinct objects that expose values through getters, then add coverage and adjust the behavior so distinct instances are not treated as equal; the relevant tests should pass afterward.

Written by the indexing model from the issue text.

Assessment

Tech stack
react, typescript
Domain
frontend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
52/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.