Tips for monitoring multiple values in a Vue 3 script setup

Question

Tips for monitoring multiple values in a Vue 3 script setup

Within my code, I currently have a watcher set up like this (inside <script setup>):

const form = reactive({
    body: '',
    image: ''
})

watch(() => form.image, () => {
    console.log(form.image)
})

I am looking to enhance this watcher by monitoring two reactive objects simultaneously:

watch(() => (form.image, form.body), () => {
    console.log(form)
})

However, it seems that only form.body is being watched now. I have attempted to follow the guidance from this question's answer, but it does not function the same way as my original watcher in terms of capturing both new and old values. My objective is for the watcher to activate only when both values are updated.

javascript vue.js events vuejs3 watch

Answer 1

Answer №1

I made a discovery. It will activate when both conditions are met. You have the flexibility to customize the conditions as needed.

const form = reactive({
    body: '',
    image: ''
})

watch(() => [form.image, form.body], () => {
    if (form.image && form.body) {
        console.log(form)
    }
})

This approach appears effective for straightforward scenarios but may encounter issues in larger codebases with extensive use of global proxies and multiple proxies. In my experience, it worked inconsistently when tested with 4 global proxies in a complex project.

Building on @tao's suggestion in the comments, remember to include { deep: true } in your watcher configuration when dealing with nested objects.

For more information on deep watchers, refer to the Vue.js documentation.

Answer 2

I made a discovery. It will activate when both conditions are met. You have the flexibility to customize the conditions as needed.

const form = reactive({
    body: '',
    image: ''
})

watch(() => [form.image, form.body], () => {
    if (form.image && form.body) {
        console.log(form)
    }
})

This approach appears effective for straightforward scenarios but may encounter issues in larger codebases with extensive use of global proxies and multiple proxies. In my experience, it worked inconsistently when tested with 4 global proxies in a complex project.

Building on @tao's suggestion in the comments, remember to include { deep: true } in your watcher configuration when dealing with nested objects.

For more information on deep watchers, refer to the Vue.js documentation.

Answer 3

Answer №2

To monitor multiple values simultaneously, you will need to use watch each time:

watch(() => form.image, () => {
    console.log(form.image)
})
watch(() => form.body, () => {
    console.log(form.body)
})

If you want a single watcher for both variables, do this instead:

watch([() => form.image, () => form.body], 
([newImage, newBody], [prevImage, prevBody]) => {
    console.log(form.body, form.image)
})

An example of this can be found in the following answer: from the linked question.

Answer 4

To monitor multiple values simultaneously, you will need to use watch each time:

watch(() => form.image, () => {
    console.log(form.image)
})
watch(() => form.body, () => {
    console.log(form.body)
})

If you want a single watcher for both variables, do this instead:

watch([() => form.image, () => form.body], 
([newImage, newBody], [prevImage, prevBody]) => {
    console.log(form.body, form.image)
})

An example of this can be found in the following answer: from the linked question.

Answer 5

Answer №3

If you want to monitor reactivity, consider using the watchEffect function:

watchEffect(() => {
  emit('update:selectedProduct', localSelectedProduct.value);
  emit('update:selectedOffer', localSelectedOffer.value);
});

For more information, refer to the documentation on vuejs: https://vuejs.org/guide/essentials/watchers.html#watcheffect

Answer 6

If you want to monitor reactivity, consider using the watchEffect function:

watchEffect(() => {
  emit('update:selectedProduct', localSelectedProduct.value);
  emit('update:selectedOffer', localSelectedOffer.value);
});

For more information, refer to the documentation on vuejs: https://vuejs.org/guide/essentials/watchers.html#watcheffect

Tips for monitoring multiple values in a Vue 3 script setup

Answer №1

Answer №2

Answer №3

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