I have this watcher (inside <script setup>:

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

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

which I want to expand to watch two reactive objects:

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

but this now only watches form.body. I've been trying to implement this question's answer, but it doesn't seem to work like my watcher with new and old values. I want the watcher to trigger, when both values are updated.

I have this watcher (inside <script setup>:

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

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

which I want to expand to watch two reactive objects:

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

but this now only watches form.body. I've been trying to implement this question's answer, but it doesn't seem to work like my watcher with new and old values. I want the watcher to trigger, when both values are updated.

• javascript
• vue.js
• events
• vuejs3
• watch

3 Answers 3

I figured something out. It'll trigger when both values are true. You can put your own conditions in there.

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

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

Like @tao suggested in the comments, if you're working with nested objects, you have to use { deep: true } in your watcher.

More about deep watchers in the vue docs.

You need to call watch each time if you need multiple watchers:

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

if what you need is a watcher to watch the two then :

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

if we take example on that answer : https://stackoverflow.com/a/45853349/8126784 from the question you linked

This can be done with watchEffect it will check the reactivity:

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

Here's the vuejs docs: https://vuejs.org/guide/essentials/watchers.html#watcheffect