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refWithControl

packages/shared/refWithControl/index.md

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refWithControl

Fine-grained controls over ref and its reactivity.

Usage

refWithControl uses extendRef to provide two extra functions get and set to have better control over when it should track/trigger the reactivity.

ts
import { refWithControl } from '@vueuse/core'

const num = refWithControl(0)
const doubled = computed(() => num.value * 2)

// just like normal ref
num.value = 42
console.log(num.value) // 42
console.log(doubled.value) // 84

// set value without triggering the reactivity
num.set(30, false)
console.log(num.value) // 30
console.log(doubled.value) // 84 (doesn't update)

// get value without tracking the reactivity
watchEffect(() => {
  console.log(num.peek())
}) // 30

num.value = 50 // watch effect wouldn't be triggered since it collected nothing.
console.log(doubled.value) // 100 (updated again since it's a reactive set)

peek, lay, untrackedGet, silentSet

We also provide some shorthands for doing the get/set without track/triggering the reactivity system. The following lines are equivalent.

ts
import { refWithControl } from '@vueuse/core'
// ---cut---
const foo = refWithControl('foo')
ts
import { refWithControl } from '@vueuse/core'

const foo = refWithControl('foo')
// ---cut---
// getting
foo.get(false)
foo.untrackedGet()
foo.peek() // an alias for `untrackedGet`
ts
import { refWithControl } from '@vueuse/core'

const foo = refWithControl('foo')
// ---cut---
// setting
foo.set('bar', false)
foo.silentSet('bar')
foo.lay('bar') // an alias for `silentSet`

Configurations

onBeforeChange()

onBeforeChange option is offered to give control over if a new value should be accepted. For example:

ts
import { refWithControl } from '@vueuse/core'
// ---cut---
const num = refWithControl(0, {
  onBeforeChange(value, oldValue) {
    // disallow changes larger then ±5 in one operation
    if (Math.abs(value - oldValue) > 5)
      return false // returning `false` to dismiss the change
  },
})

num.value += 1
console.log(num.value) // 1

num.value += 6
console.log(num.value) // 1 (change been dismissed)

onChanged()

onChanged option offers a similar functionally as Vue's watch but being synchronized with less overhead compared to watch.

ts
import { refWithControl } from '@vueuse/core'
// ---cut---
const num = refWithControl(0, {
  onChanged(value, oldValue) {
    console.log(value)
  },
})