VueUse
Add to 7 to show the alert.

Count: 0

until

Promised one-time watch for changes

Usage

Wait for some async data to be ready

import { until, useAsyncState } from '@vueuse/core'

const { state, ready } = useAsyncState(
  fetch('https://jsonplaceholder.typicode.com/todos/1').then(t => t.json()),
  {},
)

;(async() => {
  await until(ready).toBe(true)

  console.log(state) // state is now ready!
})()

Wait for custom conditions

You can use invoke to call the async function.

import { until, useCounter, invoke } from '@vueuse/core'

const { count } = useCounter()

invoke(async() => {
  await until(count).toMatch(v => v > 7)

  alert('Counter is now larger than 7!')
})

Timeout

// will be resolve until ref.value === true or 1000ms passed
await until(ref).toBe(true, { timeout: 1000 })

// will throw if timeout
try {
  await until(ref).toBe(true, { timeout: 1000, throwOnTimeout: true })
  // ref.value === true
} catch(e) {
  // timeout
}

More Examples

await until(ref).toBe(true)
await until(ref).toMatch(v => v > 10 && v < 100)
await until(ref).changed()
await until(ref).changedTimes(10)
await until(ref).toBeTruthy()
await until(ref).toBeNull()

await until(ref).not.toBeNull()
await until(ref).not.toBeTruthy()

Type Declarations

export interface UntilToMatchOptions {
  /**
   * Milliseconds timeout for promise to resolve/reject if the when condition does not meet.
   * 0 for never timed out
   *
   * @default 0
   */
  timeout?: number
  /**
   * Reject the promise when timeout
   *
   * @default false
   */
  throwOnTimeout?: boolean
  /**
   * `flush` option for internal watch
   *
   * @default 'sync'
   */
  flush?: WatchOptions["flush"]
  /**
   * `deep` option for internal watch
   *
   * @default 'false'
   */
  deep?: WatchOptions["deep"]
}
export interface UntilBaseInstance<T> {
  toMatch(
    condition: (v: T) => boolean,
    options?: UntilToMatchOptions
  ): Promise<void>
  changed(options?: UntilToMatchOptions): Promise<void>
  changedTimes(n?: number, options?: UntilToMatchOptions): Promise<void>
}
export interface UntilValueInstance<T> extends UntilBaseInstance<T> {
  readonly not: UntilValueInstance<T>
  toBe<P = T>(
    value: MaybeRef<T | P>,
    options?: UntilToMatchOptions
  ): Promise<void>
  toBeTruthy(options?: UntilToMatchOptions): Promise<void>
  toBeNull(options?: UntilToMatchOptions): Promise<void>
  toBeUndefined(options?: UntilToMatchOptions): Promise<void>
  toBeNaN(options?: UntilToMatchOptions): Promise<void>
}
export interface UntilArrayInstance<T> extends UntilBaseInstance<T> {
  readonly not: UntilArrayInstance<T>
  toContains(
    value: MaybeRef<ElementOf<ShallowUnwrapRef<T>>>,
    options?: UntilToMatchOptions
  ): Promise<void>
}
/**
 * Promised one-time watch for changes
 *
 * @see /until
 * @example
 * ```
 * const { count } = useCounter()
 *
 * await until(count).toMatch(v => v > 7)
 *
 * alert('Counter is now larger than 7!')
 * ```
 */
export declare function until<T extends unknown[]>(
  r: WatchSource<T> | MaybeRef<T>
): UntilArrayInstance<T>
export declare function until<T>(
  r: WatchSource<T> | MaybeRef<T>
): UntilValueInstance<T>
/**
 * @deprecated `when` is renamed to `util`, use [`until`](/shared/until/)instead. This will be removed in next major version.
 */
export declare const when: typeof until

Source

Source • Demo • Docs