Overview

TanStack Pacer is a library focused on providing high-quality utilities for controlling function execution timing in your applications. While similar utilities exist elsewhere, we aim to get all the important details right - including type-safety, tree-shaking, and a consistent and intuitive API. By focusing on these fundamentals and making them available in a framework agnostic way, we hope to make these utilities and patterns more commonplace in your applications. Proper execution control is often an afterthought in application development, leading to performance issues, race conditions, and poor user experiences that could have been prevented. TanStack Pacer helps you implement these critical patterns correctly from the start!

Many of the ideas (and code) for TanStack Pacer are not new. In fact, many of these utilities have been living in other TanStack libraries for quite some time. We extracted code from TanStack Query, Router, Form, and even Tanner's original Swimmer library. Then we cleaned up these utilities, filled in some gaps, and shipped them as a standalone library.

• Debouncing
  • Delay execution until after a period of inactivity for when you only care about the last execution in a sequence.
  • Synchronous or Asynchronous Debounce utilities with promise support and error handling
  • Control of leading, trailing, and enabled options
• Throttling
  • Smoothly limit the rate at which a function can fire
  • Synchronous or Asynchronous Throttle utilities with promise support and error handling
  • Control of leading, trailing, and enabled options.
• Rate Limiting
  • Limit the rate at which a function can fire over a period of time
  • Synchronous or Asynchronous Rate Limiting utilities with promise support and error handling
  • Fixed or Sliding Window variations of Rate Limiting
• Queuing
  • Queue functions to be executed in a specific order
  • Choose from FIFO, LIFO, and Priority queue implementations
  • Control processing speed with configurable wait times or concurrency limits
  • Manage queue execution with start/stop capabilities
  • Expire items from the queue after a configurable duration
• Batching
  • Chunk up multiple operations into larger batches to reduce total back-and-forth operations
  • Batch by time period, batch size, whichever comes first, or a custom condition to trigger batch executions
• Async or Sync Variations
  • Choose between synchronous and asynchronous versions of each utility
  • Optional error, success, and settled handling for async variations
  • Retry and Abort support for async variations
• State Management
  • Uses TanStack Store under the hood for state management with fine-grained reactivity
  • Easily integrate with your own state management library of choice
  • Persist state to local or session storage for some utilities like rate limiting and queuing
• Convenient Hooks
  • Reduce boilerplate code with pre-built hooks like useDebouncedCallback, useThrottledValue, and useQueuedState, and more.
  • Multiple layers of abstraction to choose from depending on your use case.
  • Works with each framework's default state management solutions, or with whatever custom state management library that you prefer.
• Type Safety
  • Full type safety with TypeScript that makes sure that your functions will always be called with the correct arguments
  • Generics for flexible and reusable utilities
• Framework Adapters
  • React, Solid, and more
• Tree Shaking
  • We, of course, get tree-shaking right for your applications by default, but we also provide extra deep imports for each utility, making it easier to embed these utilities into your libraries without increasing the bundle-phobia reports of your library.

Each utility is designed to be used in a specific way, and each utility has its own unique behavior.

See how each utility behaves with this interactive comparison. Move the range slider to observe the differences between debouncing, throttling, rate limiting, queuing, and batching:

Pacer Lite (@tanstack/pacer-lite) is a stripped down version of the core TanStack Pacer library. It is designed to be used in libraries and npm packages that need minimal overhead, and no reactivity features. The Lite version of each utility has the same core functionality of its core counterpart, but is stripped down to have a slightly smaller API surface and a smaller bundle size. Pacer Lite lacks reactivity features, framework adapters, devtools support, and some of the advanced options that the core utilities have. If that sounds interesting to you, you can