Dynamic attribute names in Vue - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What attribute does this Vue component render dynamically?

Consider this Vue 3 component using the Composition API. What attribute will the rendered <input> element have?

Vue

<template>
  <input v-bind:[dynamicAttr]="inputValue" />
</template>

<script setup>
import { ref } from 'vue'
const dynamicAttr = 'placeholder'
const inputValue = ref('Enter your name')
</script>

A An input with a placeholder attribute set to 'Enter your name'

B An input with a value attribute set to 'Enter your name'

C An input with a dynamicAttr attribute set to 'Enter your name'

D An input with no attributes set

💡 Hint

Look at how the attribute name is set using square brackets inside the binding.

The syntax v-bind:[dynamicAttr] means Vue will use the value of the variable dynamicAttr as the attribute name. Since dynamicAttr is 'placeholder', the input will have a placeholder attribute with the value from inputValue.

📝 Syntax

intermediate

Which option correctly binds a dynamic attribute in Vue 3?

Which of the following Vue template bindings correctly sets a dynamic attribute name stored in attrName with value attrValue?

A <input v-bind:attrName="attrValue" />

B <input :attrName="attrValue" />

C <input :[attrName]="attrValue" />

D <input v-bind:[attrName]="attrValue" />

💡 Hint

Remember that dynamic attribute names require square brackets inside the binding directive.

Option D uses v-bind:[attrName] which is the correct syntax for dynamic attribute names in Vue. Option D is also valid shorthand syntax for dynamic attribute names. Option D and C bind literally to an attribute named 'attrName'.

🔧 Debug

advanced

Why does this dynamic attribute binding not work as expected?

Given this Vue 3 component snippet, why does the dynamic attribute not appear on the <button> element?

Vue

<template>
  <button :[attr]="true">Click me</button>
</template>

<script setup>
const attr = null
</script>

A Because the value true is invalid for any attribute

B Because the button element does not support dynamic attributes

C Because <code>attr</code> is null, Vue cannot set a dynamic attribute with a null name

D Because dynamic attributes require the value to be a string

💡 Hint

Check the value of the variable used for the attribute name.

Vue uses the value of attr as the attribute name. Since attr is null, Vue cannot create an attribute with a null name, so no attribute is rendered.

❓ state_output

advanced

What is the rendered output after clicking the button?

In this Vue 3 component, clicking the button toggles the dynamic attribute name. What attribute does the button have after the first click?

Vue

<template>
  <button :[attrName]="true" @click="toggle">Toggle</button>
</template>

<script setup>
import { ref } from 'vue'
const attrName = ref('disabled')
function toggle() {
  attrName.value = attrName.value === 'disabled' ? 'aria-pressed' : 'disabled'
}
</script>

A The button has the attribute disabled="true"

B The button has the attribute aria-pressed="true"

C The button has both disabled and aria-pressed attributes

D The button has no attributes

💡 Hint

Think about how the attribute name changes after the click.

Initially, attrName is 'disabled'. After the first click, it changes to 'aria-pressed'. The button then has aria-pressed="true" and no longer has the disabled attribute.

🧠 Conceptual

expert

Why use dynamic attribute names in Vue components?

Which of the following best explains a practical reason to use dynamic attribute names in Vue?

A To conditionally bind different HTML attributes based on component state or props without repeating code

B To enable two-way data binding on any attribute automatically

C To improve performance by avoiding re-rendering of static attributes

D To allow Vue to generate unique attribute names for CSS styling

💡 Hint

Think about why you might want to change attribute names dynamically instead of hardcoding them.

Dynamic attribute names let you reuse the same binding logic to set different attributes depending on conditions, making components more flexible and reducing repeated code.