Ember Adapter

The ember-pacer adapter connects Pacer scheduling utilities to Ember state and lifecycle management. It re-exports the core package, including utility classes, stateless functions, option types, and async retrying.

Installation#

pnpm add @tanstack/ember-pacer

The package is ESM-only and requires Node.js 20 or newer when running in Node.js.

Lifecycle and state#

Call the use* template helpers inside a {{#let}} block. The execution callback is the first positional argument and the optional state selector is the second. Pass options as named arguments. Ember tracks named arguments and updates the same utility after rendering. Removing the helper from the template releases its subscriptions and cleans up pending work.

By default, the selected state is {}. Pass a selector to subscribe only to the fields your UI reads. The underlying store remains available for additional subscriptions.

API overview#

Example#

This counter coalesces rapid clicks into one update after 500 ms. Flush applies the latest pending count immediately.

import Component from '@glimmer/component'
import { tracked } from '@glimmer/tracking'
import { on } from '@ember/modifier'
import { fn } from '@ember/helper'
import { useDebouncer } from '@tanstack/ember-pacer'
import type { DebouncerState, EmberDebouncer } from '@tanstack/ember-pacer'

export default class Counter extends Component {
  @tracked count = 0
  @tracked debouncedCount = 0
  execute = (value: number) => {
    this.debouncedCount = value
  }
  select = (state: DebouncerState<(value: number) => void>) => ({
    isPending: state.isPending,
  })
  increment = (debouncer: EmberDebouncer<(value: number) => void>) => {
    debouncer.maybeExecute(++this.count)
  }

  <template>
    {{#let (useDebouncer this.execute this.select wait=500) as |debouncer|}}
      <button {{on 'click' (fn this.increment debouncer)}}>Increment</button>
      <p>Count: {{this.count}}. Debounced: {{this.debouncedCount}}.</p>
      <p>Pending: {{debouncer.state.isPending}}</p>
      <button {{on 'click' debouncer.flush}}>Flush</button>
    {{/let}}
  </template>
}

Child subscriptions#

Invoke the contextual utility.Subscribe helper with a selector. Reading its result in a template tracks only that selection; removing the helper releases the subscription.

{{#let (debouncer.Subscribe this.select) as |state|}}
  <span>Pending: {{state.isPending}}</span>
{{/let}}

Reactive options#

Pass tracked values directly as named arguments, for example wait=this.wait. A scope created by createPacerScope(() => defaults) supplies contextual helpers with shared defaults. Pass the scope through component arguments to share it. Local named options take precedence.

Options retain the core partial-merge behavior. Omitting a key preserves the previous setting; explicitly passing undefined clears it. key, initialState, and initialItems initialize the utility once and do not recreate it on later updates.

Default options#

createPacerScope returns typed contextual helpers. Invoke scope.useDebouncer with normal positional and named arguments. Scope defaults can be a factory or an object with getters. Each helper owns its cleanup.

Cleanup#

Debouncers, throttlers, and batchers cancel pending timers by default. Queuers stop processing. Async variants also abort active work. Synchronous rate limiters need no timer cleanup.

Set onUnmount to replace the default cleanup, for example to call flush() before leaving a page. The callback receives the adapter instance and its selected state. If you replace cleanup for an async utility, call its cancellation or abort methods when needed.

Event handlers and value helpers#

Use an instance method as the event handler: maybeExecute for debouncing, throttling, and rate limiting, or addItem for batching. The instance also provides control methods and state subscriptions.

State and value helpers return an object with value, setValue, and utility. Read value in the template so Ember tracks it. State helpers initialize once; value helpers process changes to their positional input. Queue state helpers return the queue with items selected by default.

Async utilities#

The five async utilities preserve typed results and core error behavior. Use onSuccess, onError, and onSettled for outcomes, and asyncRetryerOptions for retry configuration. abort() is cooperative: your operation must observe the supplied abort signal. See the individual async guides for scheduling and concurrency details.

Devtools#

Install @tanstack/devtools and @tanstack/pacer-devtools. Mount TanStackDevtoolsCore with plugins: [pacerDevtoolsPlugin()] once in your application and unmount it during cleanup. Give each utility a key to make it appear in the Pacer panel.

See the devtools setup guide for this framework's mount and cleanup code.

API reference#

See the generated reference for signatures, options, and return types.