(1/12) Which Composition API function allows you to watch multiple reactive sources at once?

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• multiWatch()
• watchArray()
• watch() with an array of sources
• watchMulti()

(2/12) What is the recommended approach if you need to re-run a watch callback in Vue 3 while preserving the oldValue/newValue arguments each time?

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• Use a watch with a proper source function or ref, so the callback receives (newVal, oldVal). Then rely on reactivity changes to re-trigger it.
• Use watchEffect to forcibly re-run everything
• Watchers cannot preserve old values in Vue 3
• Inline watchers in the template with a method call

(3/12) What is the correct usage of the 'unref()' function in Vue 3?

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• Returns the raw .value if the argument is a ref, otherwise returns the argument as is
• Stops a watcher from tracking a ref
• Extracts nested properties from a reactive object
• Converts an object into a ref

(4/12) What is the main difference between watchEffect() and watch() when you only pass a ref as the first argument in watch()?

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• watchEffect cannot clean up async tasks
• watchEffect automatically collects all used refs in the callback; watch(ref, callback) tracks only that ref explicitly
• They are identical in how dependencies are tracked
• watch() only works with arrays, watchEffect only with single refs

(5/12) Which Vue Router feature lets you add custom data to a route definition, such as requiring authentication or specifying layout types?

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• router transforms
• route mixins
• route watchers
• meta fields

(6/12) Which statement about using template refs in a Vue 3 Single File Component with <script setup> is correct?

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• You must manually return them from setup() to use them in the template
• Refs are not allowed in <script setup>
• Refs can only be used in functional components
• Declaring const myRef = ref(null) at top-level, then <div ref="myRef" /> is enough; no additional return is needed

(7/12) In Vue 3, how do you create a global mixin that logs a message whenever any component is mounted?

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• Use a custom directive for logging
• Global mixins are removed in Vue 3
• Define watchers in main.js
• app.mixin({ mounted() { console.log('Component mounted'); } })

(8/12) When referencing route params that can be optional, how do you define watchers in Vue 3 to handle the possibility that route.params.userId might be undefined?

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• Use watch(() => route.params.userId, (newVal, oldVal) => { if (newVal) ... }). The callback sees undefined if param is missing
• Use watchers in main.js for concurrency watchers only
• You cannot watch optional params
• Use defineProps for concurrency watchers

(9/12) If you need to watch multiple reactive variables in a single callback in Vue 3, how can you do it succinctly?

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• Use watchEffect with multiple references inside the callback
• Use v-model on each variable
• Use watchers for each variable separately only
• Define a single custom directive for them all

(10/12) What does the 'emits' option in a Vue 3 component define?

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• Which DOM events a component listens to by default
• Which custom events a component might emit
• Which data properties are reactive
• Which watchers a component can create

(11/12) Which statement describes a scenario where watchPostEffect in Vue 3 might be more appropriate than watchEffect?

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• When you want to block rendering until the effect completes
• They are identical in every usage scenario
• When you need to run the effect after the DOM has been patched (e.g., reading post-update DOM state)
• When you need a deep watcher on an object

(12/12) Which is an example of properly typing props using defineProps in a Vue 3 component with TypeScript?

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• const props = defineProps<any>() // no checking
• const props = defineProps<{title: string; count?: number}>()
• defineProps cannot be used with TypeScript
• Use onMounted for type definitions

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