The request asks for a promise timer for React, which none of the candidates is a dedicated library for; the nearest fits are Sentry React for timing and performance tracing in React apps 111, AI SDK React for React streaming and async UI state 2, and ReactiveX for asynchronous event streams and time-based operators 4. Please confirm whether you mean a timer utility for promises (e.g. a timeout or delay wrapper) or performance timing, as the candidates differ.

A question back: Do you want a utility that adds a timeout or delay to a promise in React, or do you want to measure how long promises and renders take?

1. 1

   Sentry Reactsentry.ioverified and signed

   Sentry's React SDK (@sentry/react) sets up error monitoring, tracing and performance instrumentation for React apps 111.

   WebsiteDocsPricingGet started

   official:SDK · @sentry/reactskill · sentry-react-sdkSDK · @sentry/react-routerskill · sentry-react-router-framework-sdkskill · sentry-react-setup

   for agents: sentry-react-sdk · sentry-react-sdk · sentry-react-setup

2. 2

   ReactiveXreactivex.iowebsite read, tools not yet checked

   ReactiveX offers operators for handling asynchronous work over observable streams, including on the frontend with RxJS, which can express timed and delayed promise-like flows 4.

   WebsiteDocs

3. 3

   AI SDK Reactai-sdk.devverified and signed

   The AI SDK's React package (@ai-sdk/react) handles streaming and asynchronous state in React chat and AI interfaces 2.

   WebsiteDocs

   official:SDK · @ai-sdk/react

   for agents: react · ai