Dynamic components with is attribute in Vue - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What will this Vue dynamic component render?

Given the following Vue 3 component setup, what will be rendered inside the <component :is="currentComp" />?

Vue

<template>
  <component :is="currentComp" />
</template>

<script setup>
import { ref } from 'vue'

const HelloComp = {
  template: '<p>Hello!</p>'
}

const ByeComp = {
  template: '<p>Goodbye!</p>'
}

const currentComp = ref(HelloComp)
</script>

A <p>Goodbye!</p>

B <p>Hello!</p>

C Nothing renders because components are not globally registered

D Error: Unknown component 'HelloComp'

💡 Hint

Think about what the is attribute does and how the component name is resolved.

The component tag with :is="currentComp" renders the component referenced by currentComp. Since currentComp holds HelloComp, which is locally defined, Vue renders its template: Hello!.

❓ state_output

intermediate

What is the value of currentComp after clicking the button?

Consider this Vue 3 component:

<template>
  <component :is="currentComp" />
  <button @click="toggleComp">Toggle</button>
</template>

<script setup>
import { ref } from 'vue'

const currentComp = ref('CompA')

function toggleComp() {
  currentComp.value = currentComp.value === 'CompA' ? 'CompB' : 'CompA'
}
</script>

Initially, currentComp is 'CompA'. What is its value after the button is clicked twice?

A Error: currentComp is not reactive

B CompB

C CompA

D undefined

💡 Hint

Each click toggles the component name. Think about toggling twice.

The toggleComp function switches currentComp between 'CompA' and 'CompB'. Starting at 'CompA', one click changes it to 'CompB', the second click changes it back to 'CompA'.

📝 Syntax

advanced

Which option correctly uses the is attribute with a dynamic component in Vue 3?

Choose the correct syntax to render a dynamic component using the is attribute bound to a variable currentView.

A <component v-bind:is="currentView" />

B <component is="currentView" />

C <component :is='currentView'/>

D <component :is="currentView" />

💡 Hint

Remember how to bind attributes dynamically in Vue templates.

In Vue, to bind an attribute dynamically, you use : (shorthand) or v-bind:. Option D uses the preferred shorthand :is="currentView". Option D treats is as a static string, not dynamic. Option D uses full v-bind:is="currentView", which works but is more verbose. Option D uses single quotes for the expression, which is valid but Vue style guide prefers double quotes for attribute values.

🔧 Debug

advanced

Why does this dynamic component fail to render?

Given this Vue 3 code snippet:

<template>
  <component :is="currentComp" />
</template>

<script setup>
import { ref } from 'vue'

const MyComp = {
  template: '<p>Hi there</p>'
}

const currentComp = ref('MyComp')
</script>

Why does the component not render and show an error?

A MyComp is not registered globally or locally, so Vue cannot find it

B The template string in MyComp is invalid HTML

C The ref variable currentComp should not be reactive for dynamic components

D The component tag must be self-closing with a slash

💡 Hint

Think about how Vue finds components by name.

Vue needs components to be registered either globally or locally to render them by name. Here, MyComp is defined but not registered or exposed, so Vue cannot find it when currentComp is 'MyComp'.

🧠 Conceptual

expert

What is the main advantage of using the is attribute for dynamic components in Vue?

Choose the best explanation for why Vue developers use the is attribute to render dynamic components.

A It allows switching between different components at runtime without changing the template structure

B It improves performance by caching all components automatically

C It forces Vue to render components only once and never update them

D It enables using components without importing or registering them

💡 Hint

Think about flexibility in UI rendering.

The is attribute lets Vue render different components dynamically based on data or state. This means you can switch which component shows without rewriting the template, making UI flexible and easier to manage.

Practice

1. What does the is attribute do in Vue's <component> tag?

easy

A. It binds data to the component's props.

B. It sets the CSS style of the component.

C. It tells Vue which component to render dynamically.

D. It triggers a lifecycle hook in the component.

Solution

1. Step 1: Understand the role of <component> tag

   The <component> tag in Vue is a special tag used to render different components dynamically.

2. Step 2: Identify the purpose of the is attribute

   The is attribute specifies which component to render by binding to a variable or string representing the component name.

3. Final Answer:

   It tells Vue which component to render dynamically. -> Option C

4. Quick Check:

   Dynamic component selection = is attribute [OK]

Hint: Remember: picks component x [OK]

Common Mistakes:

• Thinking is sets styles
• Confusing is with prop binding
• Assuming is triggers lifecycle hooks

2. Which of the following is the correct syntax to use a dynamic component named MyButton in Vue?

easy

A.

B.

C.

D.

Solution

1. Step 1: Understand binding syntax for dynamic components

   The is attribute must be bound with : to a variable or string. To specify a component by name as a string, use quotes inside the binding.

2. Step 2: Check each option's syntax

   uses is="MyButton" without binding, so Vue treats it as a literal tag, not a component name. binds MyButton as a variable, but if MyButton is not defined in the script, it fails. correctly binds is to the string 'MyButton'. uses is='MyButton' without binding, which is invalid for dynamic components.

3. Final Answer:

   <component :is='"MyButton"'></component> -> Option A

4. Quick Check:

   Use :is with quotes for string component names [OK]

Hint: Use :is with quotes for string names, no quotes without : [OK]

Common Mistakes:

• Omitting the colon for binding
• Using quotes without binding
• Binding to undefined variables

3. Given the Vue template:

<template>
  <component :is="currentView" />
</template>

<script setup>
import HomeView from './HomeView.vue'
import AboutView from './AboutView.vue'

const currentView = ref('HomeView')
</script>

What will be rendered initially?

medium

A. The HomeView component

B. The AboutView component

C. A runtime error because currentView is a string

D. An empty component (nothing rendered)

Solution

1. Step 1: Analyze the value of currentView

   The variable currentView is a ref holding the string 'HomeView'.

2. Step 2: Understand how Vue resolves dynamic components

   Vue expects the is attribute to be a component object or a registered component name. Here, 'HomeView' is a string but the component is imported as HomeView object, not registered globally or locally by that string name.

3. Step 3: Result of passing string without registration

   Since 'HomeView' is not registered as a component name, Vue renders nothing (empty component) without error.

4. Final Answer:

   An empty component (nothing rendered) -> Option D

5. Quick Check:

   Unregistered string name = empty render [OK]

Hint: Dynamic component string must be registered or component object [OK]

Common Mistakes:

• Assuming string name auto-resolves to imported component
• Expecting runtime error for string value
• Confusing ref value with component object

4. Identify the error in this Vue code snippet:

<template>
  <component :is="currentComp" />
</template>

<script setup>
import Foo from './Foo.vue'

const currentComp = Foo
</script>

medium

A. No error; this code works correctly

B. The currentComp variable should be a string, not a component object

C. Missing quotes around component name in is attribute

D. The component tag must be self-closing with a closing slash

Solution

1. Step 1: Check the type of currentComp

   currentComp is assigned the imported component object Foo, which is valid for dynamic components.

2. Step 2: Verify the component tag usage

   The <component> tag uses :is="currentComp" correctly, and self-closing syntax is allowed in Vue templates.

3. Final Answer:

   No error; this code works correctly -> Option A

4. Quick Check:

   Passing component object to :is works fine [OK]

Hint: Pass component objects directly to :is for dynamic rendering [OK]

Common Mistakes:

• Thinking :is must always be a string
• Confusing self-closing tags as errors
• Expecting quotes around component objects

5. You want to switch between three components HomeView, ProfileView, and SettingsView dynamically based on a button click. Which approach correctly implements this using Vue's dynamic components?

hard

A. <template>
<component :is="currentView" />
<button @click="currentView = 'HomeView'">Home</button>
<button @click="currentView = 'ProfileView'">Profile</button>
<button @click="currentView = 'SettingsView'">Settings</button>
</template>

<script setup>
import HomeView from './HomeView.vue'
import ProfileView from './ProfileView.vue'
import SettingsView from './SettingsView.vue'

const currentView = ref(HomeView)
</script>

B. <template>
<component :is="currentView" />
<button @click="currentView = HomeView">Home</button>
<button @click="currentView = ProfileView">Profile</button>
<button @click="currentView = SettingsView">Settings</button>
</template>

<script setup>
import HomeView from './HomeView.vue'
import ProfileView from './ProfileView.vue'
import SettingsView from './SettingsView.vue'

const currentView = ref(HomeView)
</script>

C. <template>
<component :is="currentView" />
<button @click="currentView = 'HomeView'">Home</button>
<button @click="currentView = 'ProfileView'">Profile</button>
<button @click="currentView = 'SettingsView'">Settings</button>
</template>

<script setup>
import HomeView from './HomeView.vue'
import ProfileView from './ProfileView.vue'
import SettingsView from './SettingsView.vue'

const currentView = ref('HomeView')
</script>

D. <template>
<component :is="currentView" />
<button @click="currentView = HomeView">Home</button>
<button @click="currentView = ProfileView">Profile</button>
<button @click="currentView = SettingsView">Settings</button>
</template>

<script setup>
import HomeView from './HomeView.vue'
import ProfileView from './ProfileView.vue'
import SettingsView from './SettingsView.vue'

const currentView = ref('HomeView')
</script>

Solution

1. Step 1: Understand how to switch components dynamically

   To switch components dynamically, currentView must hold the component object, not a string, unless the string matches a registered component name.

2. Step 2: Analyze each option's approach

   <template>
     <component :is="currentView" />
     <button @click="currentView = 'HomeView'">Home</button>
     <button @click="currentView = 'ProfileView'">Profile</button>
     <button @click="currentView = 'SettingsView'">Settings</button>
   </template>
   
   <script setup>
   import HomeView from './HomeView.vue'
   import ProfileView from './ProfileView.vue'
   import SettingsView from './SettingsView.vue'
   
   const currentView = ref(HomeView)
   </script>

   initializes currentView with a component object but sets it to strings on button clicks, causing mismatch.

   <template>
     <component :is="currentView" />
     <button @click="currentView = HomeView">Home</button>
     <button @click="currentView = ProfileView">Profile</button>
     <button @click="currentView = SettingsView">Settings</button>
   </template>
   
   <script setup>
   import HomeView from './HomeView.vue'
   import ProfileView from './ProfileView.vue'
   import SettingsView from './SettingsView.vue'
   
   const currentView = ref(HomeView)
   </script>

   initializes and updates currentView with component objects consistently, which is correct.

   <template>
     <component :is="currentView" />
     <button @click="currentView = 'HomeView'">Home</button>
     <button @click="currentView = 'ProfileView'">Profile</button>
     <button @click="currentView = 'SettingsView'">Settings</button>
   </template>
   
   <script setup>
   import HomeView from './HomeView.vue'
   import ProfileView from './ProfileView.vue'
   import SettingsView from './SettingsView.vue'
   
   const currentView = ref('HomeView')
   </script>

   uses strings only, but these strings are not registered component names, so Vue won't render them.

   <template>
     <component :is="currentView" />
     <button @click="currentView = HomeView">Home</button>
     <button @click="currentView = ProfileView">Profile</button>
     <button @click="currentView = SettingsView">Settings</button>
   </template>
   
   <script setup>
   import HomeView from './HomeView.vue'
   import ProfileView from './ProfileView.vue'
   import SettingsView from './SettingsView.vue'
   
   const currentView = ref('HomeView')
   </script>

   mixes component objects and strings inconsistently, causing errors.

3. Final Answer:

   Option B correctly uses component objects for dynamic switching. -> Option B

4. Quick Check:

   Use component objects consistently for :is switching [OK]

Hint: Keep :is value consistent: all component objects or all registered strings [OK]

Common Mistakes:

• Mixing strings and component objects in :is
• Using unregistered string names
• Initializing with object but switching to strings