Vue.js • Chapter 26 • Foundations to Advanced
Dynamic Components
Each topic includes substantial explanation, ten focused examples, its own Vue code example, step-by-step reasoning, expected behavior, and practice.
26.1 component :is
component :is is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. In Chapter 26, trace the value or control flow from its source to the rendered interface so you can explain why Vue changes the screen.
For component :is in Chapter 26, inspect reactive inputs, component ownership, rendered output, edge cases, and what causes another update. Keep writable state ownership explicit, derive values when possible, and separate display calculations from network, DOM, storage, timer, or other external work.
This lesson connects component :is to dynamic components. Start with one working case, verify the expected output, then add one edge case and explain what Vue tracks, reuses, creates, removes, or updates.
Concept in plain language
component :is is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements.
10 teaching examples
Example 1: Smallest useful case
Build the smallest analytics view that demonstrates component :is. Keep one input and one visible result, then explain reactive inputs, component ownership, rendered output, edge cases, and what causes another update. component :is is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 1 for Chapter 26, topic 1.
Example 2: Change one reactive value
Change one value involved in component :is inside the support form. Predict what Vue will update before running it, then compare the prediction with the rendered result.
Example 3: Parent-child comparison
Use component :is across two components in the course dashboard. Compare which component owns the writable data and which component only receives or presents it.
Example 4: Edge case
Add an empty, missing, invalid, delayed, or rapidly changing value to the profile editor. Handle the component :is edge case explicitly instead of leaving stale output.
Example 5: Accessibility review
Use component :is in the search panel while checking semantic HTML, labels, focus order, keyboard access, and understandable status feedback. component :is is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 5 for Chapter 26, topic 1.
Example 6: State ownership review
Remove duplicated state from the shopping cart. For component :is, derive values when possible and keep the writable source with the component or store that owns it.
Example 7: Slow-network scenario
Assume the lesson tracker has a slow request while using component :is. Decide what remains interactive, what shows pending feedback, and how stale responses are prevented.
Example 8: Refactoring exercise
Extract the component :is responsibility from a crowded booking form into a focused component or composable with a narrow API.
Example 9: Performance experiment
Measure the message panel before optimizing component :is. Check reactive work, repeated calculations, list size, component updates, and user-visible delay.
Example 10: Production review
Review component :is in the admin table for errors, security, localization, RTL, narrow screens, accessibility, and what monitoring should report. component :is is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 10 for Chapter 26, topic 1.
Vue code example
<script setup>
import { ref } from 'vue'
const topic = "component :is"
const active = ref(false)
</script>
<template>
<section><h2>{{ topic }}</h2><button :aria-pressed="active" @click="active=!active">Toggle state</button><p>{{ active ? 'Active' : 'Inactive' }}</p></section>
</template>Step-by-step code explanation
- Identify the Vue responsibility demonstrated by component :is.
- Read the reactive state, props, route/store input, or injected value before the template.
- Trace the event, dependency, watcher, lifecycle hook, or navigation action that changes the display.
- Test one normal path and one edge case, including cleanup when external work is involved.
- Confirm accessibility, mobile width, and RTL behavior for user-facing controls and translated text.
Expected behavior: A small Vue interface demonstrates component :is and updates according to the interaction or data in the example.
Practice exercise
Create a small Vue feature focused on component :is from Chapter 26. Predict the result before running it, test one edge case, and explain which reactive value, prop, event, route, store, or lifecycle step caused the update. Then check accessibility, narrow-screen width, and RTL behavior where relevant.
26.2 Switching Component Types
Switching Component Types is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. In Chapter 26, trace the value or control flow from its source to the rendered interface so you can explain why Vue changes the screen.
For Switching Component Types in Chapter 26, inspect reactive inputs, component ownership, rendered output, edge cases, and what causes another update. Keep writable state ownership explicit, derive values when possible, and separate display calculations from network, DOM, storage, timer, or other external work.
This lesson connects Switching Component Types to dynamic components. Start with one working case, verify the expected output, then add one edge case and explain what Vue tracks, reuses, creates, removes, or updates.
Concept in plain language
Switching Component Types is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements.
10 teaching examples
Example 1: Smallest useful case
Build the smallest profile editor that demonstrates Switching Component Types. Keep one input and one visible result, then explain reactive inputs, component ownership, rendered output, edge cases, and what causes another update. Switching Component Types is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 1 for Chapter 26, topic 2.
Example 2: Change one reactive value
Change one value involved in Switching Component Types inside the search panel. Predict what Vue will update before running it, then compare the prediction with the rendered result.
Example 3: Parent-child comparison
Use Switching Component Types across two components in the shopping cart. Compare which component owns the writable data and which component only receives or presents it.
Example 4: Edge case
Add an empty, missing, invalid, delayed, or rapidly changing value to the lesson tracker. Handle the Switching Component Types edge case explicitly instead of leaving stale output.
Example 5: Accessibility review
Use Switching Component Types in the booking form while checking semantic HTML, labels, focus order, keyboard access, and understandable status feedback. Switching Component Types is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 5 for Chapter 26, topic 2.
Example 6: State ownership review
Remove duplicated state from the message panel. For Switching Component Types, derive values when possible and keep the writable source with the component or store that owns it.
Example 7: Slow-network scenario
Assume the admin table has a slow request while using Switching Component Types. Decide what remains interactive, what shows pending feedback, and how stale responses are prevented.
Example 8: Refactoring exercise
Extract the Switching Component Types responsibility from a crowded photo gallery into a focused component or composable with a narrow API.
Example 9: Performance experiment
Measure the notification center before optimizing Switching Component Types. Check reactive work, repeated calculations, list size, component updates, and user-visible delay.
Example 10: Production review
Review Switching Component Types in the task board for errors, security, localization, RTL, narrow screens, accessibility, and what monitoring should report. Switching Component Types is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 10 for Chapter 26, topic 2.
Vue code example
<script setup>
import { ref } from 'vue'
const topic = "Switching Component Types"
const active = ref(false)
</script>
<template>
<section><h2>{{ topic }}</h2><button :aria-pressed="active" @click="active=!active">Toggle state</button><p>{{ active ? 'Active' : 'Inactive' }}</p></section>
</template>Step-by-step code explanation
- Identify the Vue responsibility demonstrated by Switching Component Types.
- Read the reactive state, props, route/store input, or injected value before the template.
- Trace the event, dependency, watcher, lifecycle hook, or navigation action that changes the display.
- Test one normal path and one edge case, including cleanup when external work is involved.
- Confirm accessibility, mobile width, and RTL behavior for user-facing controls and translated text.
Expected behavior: A small Vue interface demonstrates Switching Component Types and updates according to the interaction or data in the example.
Practice exercise
Create a small Vue feature focused on Switching Component Types from Chapter 26. Predict the result before running it, test one edge case, and explain which reactive value, prop, event, route, store, or lifecycle step caused the update. Then check accessibility, narrow-screen width, and RTL behavior where relevant.
26.3 Preserving Props
Preserving Props is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. In Chapter 26, trace the value or control flow from its source to the rendered interface so you can explain why Vue changes the screen.
For Preserving Props in Chapter 26, inspect component ownership, data direction, event payloads, and the public component contract. Keep writable state ownership explicit, derive values when possible, and separate display calculations from network, DOM, storage, timer, or other external work.
This lesson connects Preserving Props to dynamic components. Start with one working case, verify the expected output, then add one edge case and explain what Vue tracks, reuses, creates, removes, or updates.
Concept in plain language
Preserving Props is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements.
10 teaching examples
Example 1: Smallest useful case
Build the smallest lesson tracker that demonstrates Preserving Props. Keep one input and one visible result, then explain component ownership, data direction, event payloads, and the public component contract. Preserving Props is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 1 for Chapter 26, topic 3.
Example 2: Change one reactive value
Change one value involved in Preserving Props inside the booking form. Predict what Vue will update before running it, then compare the prediction with the rendered result.
Example 3: Parent-child comparison
Use Preserving Props across two components in the message panel. Compare which component owns the writable data and which component only receives or presents it.
Example 4: Edge case
Add an empty, missing, invalid, delayed, or rapidly changing value to the admin table. Handle the Preserving Props edge case explicitly instead of leaving stale output.
Example 5: Accessibility review
Use Preserving Props in the photo gallery while checking semantic HTML, labels, focus order, keyboard access, and understandable status feedback. Preserving Props is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 5 for Chapter 26, topic 3.
Example 6: State ownership review
Remove duplicated state from the notification center. For Preserving Props, derive values when possible and keep the writable source with the component or store that owns it.
Example 7: Slow-network scenario
Assume the task board has a slow request while using Preserving Props. Decide what remains interactive, what shows pending feedback, and how stale responses are prevented.
Example 8: Refactoring exercise
Extract the Preserving Props responsibility from a crowded language selector into a focused component or composable with a narrow API.
Example 9: Performance experiment
Measure the quiz screen before optimizing Preserving Props. Check reactive work, repeated calculations, list size, component updates, and user-visible delay.
Example 10: Production review
Review Preserving Props in the analytics view for errors, security, localization, RTL, narrow screens, accessibility, and what monitoring should report. Preserving Props is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 10 for Chapter 26, topic 3.
Vue code example
<script setup>
defineProps({ title: { type: String, required: true }, active: Boolean })
</script>
<template><article :class="{ active }"><h2>{{ title }}</h2></article></template>Step-by-step code explanation
- Identify the Vue responsibility demonstrated by Preserving Props.
- Read the reactive state, props, route/store input, or injected value before the template.
- Trace the event, dependency, watcher, lifecycle hook, or navigation action that changes the display.
- Test one normal path and one edge case, including cleanup when external work is involved.
- Confirm accessibility, mobile width, and RTL behavior for user-facing controls and translated text.
Expected behavior: A small Vue interface demonstrates Preserving Props and updates according to the interaction or data in the example.
Practice exercise
Create a small Vue feature focused on Preserving Props from Chapter 26. Predict the result before running it, test one edge case, and explain which reactive value, prop, event, route, store, or lifecycle step caused the update. Then check accessibility, narrow-screen width, and RTL behavior where relevant.
26.4 Dynamic Component Events
Dynamic Component Events is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. In Chapter 26, trace the value or control flow from its source to the rendered interface so you can explain why Vue changes the screen.
For Dynamic Component Events in Chapter 26, inspect component ownership, data direction, event payloads, and the public component contract. Keep writable state ownership explicit, derive values when possible, and separate display calculations from network, DOM, storage, timer, or other external work.
This lesson connects Dynamic Component Events to dynamic components. Start with one working case, verify the expected output, then add one edge case and explain what Vue tracks, reuses, creates, removes, or updates.
Concept in plain language
Dynamic Component Events is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements.
10 teaching examples
Example 1: Smallest useful case
Build the smallest admin table that demonstrates Dynamic Component Events. Keep one input and one visible result, then explain component ownership, data direction, event payloads, and the public component contract. Dynamic Component Events is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 1 for Chapter 26, topic 4.
Example 2: Change one reactive value
Change one value involved in Dynamic Component Events inside the photo gallery. Predict what Vue will update before running it, then compare the prediction with the rendered result.
Example 3: Parent-child comparison
Use Dynamic Component Events across two components in the notification center. Compare which component owns the writable data and which component only receives or presents it.
Example 4: Edge case
Add an empty, missing, invalid, delayed, or rapidly changing value to the task board. Handle the Dynamic Component Events edge case explicitly instead of leaving stale output.
Example 5: Accessibility review
Use Dynamic Component Events in the language selector while checking semantic HTML, labels, focus order, keyboard access, and understandable status feedback. Dynamic Component Events is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 5 for Chapter 26, topic 4.
Example 6: State ownership review
Remove duplicated state from the quiz screen. For Dynamic Component Events, derive values when possible and keep the writable source with the component or store that owns it.
Example 7: Slow-network scenario
Assume the analytics view has a slow request while using Dynamic Component Events. Decide what remains interactive, what shows pending feedback, and how stale responses are prevented.
Example 8: Refactoring exercise
Extract the Dynamic Component Events responsibility from a crowded support form into a focused component or composable with a narrow API.
Example 9: Performance experiment
Measure the course dashboard before optimizing Dynamic Component Events. Check reactive work, repeated calculations, list size, component updates, and user-visible delay.
Example 10: Production review
Review Dynamic Component Events in the profile editor for errors, security, localization, RTL, narrow screens, accessibility, and what monitoring should report. Dynamic Component Events is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 10 for Chapter 26, topic 4.
Vue code example
<script setup>
import { ref } from 'vue'
const topic = "Dynamic Component Events"
const active = ref(false)
</script>
<template>
<section><h2>{{ topic }}</h2><button :aria-pressed="active" @click="active=!active">Toggle state</button><p>{{ active ? 'Active' : 'Inactive' }}</p></section>
</template>Step-by-step code explanation
- Identify the Vue responsibility demonstrated by Dynamic Component Events.
- Read the reactive state, props, route/store input, or injected value before the template.
- Trace the event, dependency, watcher, lifecycle hook, or navigation action that changes the display.
- Test one normal path and one edge case, including cleanup when external work is involved.
- Confirm accessibility, mobile width, and RTL behavior for user-facing controls and translated text.
Expected behavior: A small Vue interface demonstrates Dynamic Component Events and updates according to the interaction or data in the example.
Practice exercise
Create a small Vue feature focused on Dynamic Component Events from Chapter 26. Predict the result before running it, test one edge case, and explain which reactive value, prop, event, route, store, or lifecycle step caused the update. Then check accessibility, narrow-screen width, and RTL behavior where relevant.
26.5 Use Cases
Use Cases is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. In Chapter 26, trace the value or control flow from its source to the rendered interface so you can explain why Vue changes the screen.
For Use Cases in Chapter 26, inspect reactive inputs, component ownership, rendered output, edge cases, and what causes another update. Keep writable state ownership explicit, derive values when possible, and separate display calculations from network, DOM, storage, timer, or other external work.
This lesson connects Use Cases to dynamic components. Start with one working case, verify the expected output, then add one edge case and explain what Vue tracks, reuses, creates, removes, or updates.
Concept in plain language
Use Cases is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements.
10 teaching examples
Example 1: Smallest useful case
Build the smallest task board that demonstrates Use Cases. Keep one input and one visible result, then explain reactive inputs, component ownership, rendered output, edge cases, and what causes another update. Use Cases is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 1 for Chapter 26, topic 5.
Example 2: Change one reactive value
Change one value involved in Use Cases inside the language selector. Predict what Vue will update before running it, then compare the prediction with the rendered result.
Example 3: Parent-child comparison
Use Use Cases across two components in the quiz screen. Compare which component owns the writable data and which component only receives or presents it.
Example 4: Edge case
Add an empty, missing, invalid, delayed, or rapidly changing value to the analytics view. Handle the Use Cases edge case explicitly instead of leaving stale output.
Example 5: Accessibility review
Use Use Cases in the support form while checking semantic HTML, labels, focus order, keyboard access, and understandable status feedback. Use Cases is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 5 for Chapter 26, topic 5.
Example 6: State ownership review
Remove duplicated state from the course dashboard. For Use Cases, derive values when possible and keep the writable source with the component or store that owns it.
Example 7: Slow-network scenario
Assume the profile editor has a slow request while using Use Cases. Decide what remains interactive, what shows pending feedback, and how stale responses are prevented.
Example 8: Refactoring exercise
Extract the Use Cases responsibility from a crowded search panel into a focused component or composable with a narrow API.
Example 9: Performance experiment
Measure the shopping cart before optimizing Use Cases. Check reactive work, repeated calculations, list size, component updates, and user-visible delay.
Example 10: Production review
Review Use Cases in the lesson tracker for errors, security, localization, RTL, narrow screens, accessibility, and what monitoring should report. Use Cases is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements. This is example 10 for Chapter 26, topic 5.
Vue code example
<script setup>
import { ref } from 'vue'
const topic = "Use Cases"
const active = ref(false)
</script>
<template>
<section><h2>{{ topic }}</h2><button :aria-pressed="active" @click="active=!active">Toggle state</button><p>{{ active ? 'Active' : 'Inactive' }}</p></section>
</template>Step-by-step code explanation
- Identify the Vue responsibility demonstrated by Use Cases.
- Read the reactive state, props, route/store input, or injected value before the template.
- Trace the event, dependency, watcher, lifecycle hook, or navigation action that changes the display.
- Test one normal path and one edge case, including cleanup when external work is involved.
- Confirm accessibility, mobile width, and RTL behavior for user-facing controls and translated text.
Expected behavior: A small Vue interface demonstrates Use Cases and updates according to the interaction or data in the example.
Practice exercise
Create a small Vue feature focused on Use Cases from Chapter 26. Predict the result before running it, test one edge case, and explain which reactive value, prop, event, route, store, or lifecycle step caused the update. Then check accessibility, narrow-screen width, and RTL behavior where relevant.
Chapter 26 review — 10 questions and answers
1. What is the purpose of component :is?
Answer: component :is is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements.
2. What should you inspect when component :is behaves unexpectedly?
Answer: Inspect reactive inputs, component ownership, rendered output, edge cases, and what causes another update. Reduce the feature to a small component and trace reactive input through the rendered result.
3. What is the purpose of Switching Component Types?
Answer: Switching Component Types is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements.
4. What should you inspect when Switching Component Types behaves unexpectedly?
Answer: Inspect reactive inputs, component ownership, rendered output, edge cases, and what causes another update. Reduce the feature to a small component and trace reactive input through the rendered result.
5. What is the purpose of Preserving Props?
Answer: Preserving Props is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements.
6. What should you inspect when Preserving Props behaves unexpectedly?
Answer: Inspect component ownership, data direction, event payloads, and the public component contract. Reduce the feature to a small component and trace reactive input through the rendered result.
7. What is the purpose of Dynamic Component Events?
Answer: Dynamic Component Events is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements.
8. What should you inspect when Dynamic Component Events behaves unexpectedly?
Answer: Inspect component ownership, data direction, event payloads, and the public component contract. Reduce the feature to a small component and trace reactive input through the rendered result.
9. What is the purpose of Use Cases?
Answer: Use Cases is a focused part of Vue application design in Chapter 26. Study its inputs, reactive dependencies, component ownership, rendered result, edge cases, and cleanup requirements.
10. What should you inspect when Use Cases behaves unexpectedly?
Answer: Inspect reactive inputs, component ownership, rendered output, edge cases, and what causes another update. Reduce the feature to a small component and trace reactive input through the rendered result.