whenever

分类

导出大小

173 B

上次更改

去年

当值为真值时，进行监听的简写。

用法

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

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

whenever(isReady, () => console.log(state))

// this
whenever
(ready, () => console
.log
(state))

// is equivalent to:
watch
(ready, (isReady
) => {
  if (isReady
)
    console
.log
(state)
})

回调函数

与 watch 相同，回调函数将被调用，参数为 cb(value, oldValue, onInvalidate)。

whenever
(height, (current
, lastHeight
) => {
  if (current
 > lastHeight
)
    console
.log
(`Increasing height by ${current
 - lastHeight
}`)
})

计算属性

与 watch 相同，你可以传入一个 getter 函数来在每次更改时进行计算。

// this
whenever
(
  () => counter.value === 7,
  () => console
.log
('counter is 7 now!'),
)

选项

选项和默认值与 watch 相同。

// this
whenever
(
  () => counter.value === 7,
  () => console
.log
('counter is 7 now!'),
  { flush
: 'sync' },
)

类型声明

export interface WheneverOptions extends WatchOptions {
  /**
   * Only trigger once when the condition is met
   *
   * Override the `once` option in `WatchOptions`
   *
   * @default false
   */
  once
?: boolean
}
/**
 * Shorthand for watching value to be truthy
 *
 * @see https://vueuse.org.cn/whenever
 */
export declare function whenever
<T
>(
  source
: WatchSource
<T
 | false | null | undefined>,
  cb
: WatchCallback
<T
>,
  options
?: WheneverOptions,
): WatchHandle