Template refs for DOM access in Vue - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a template ref named 'inputRef'.

Vue

<template>
  <input type="text" ref="[1]" />
</template>

Drag options to blanks, or click blank then click option'

AinputRef

BmyRef

CtextInput

DrefInput

Attempts:

3 left

💡 Hint

Common Mistakes

Using a ref name that doesn't match the script variable.

Forgetting to add the ref attribute.

The ref attribute in the template defines the name of the template ref. Here, it should be inputRef to match the usage.

2fill in blank

medium

Complete the code to import the correct function to create a template ref in Vue 3.

Vue

<script setup>
import { [1] } from 'vue'
const inputRef = [1](null)
</script>

Drag options to blanks, or click blank then click option'

Aref

Breactive

Ccomputed

Dwatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using reactive instead of ref for DOM refs.

Forgetting to import the function.

The ref function is used to create a reactive reference to a DOM element or value in Vue 3.

3fill in blank

hard

Fix the error in accessing the DOM element's value using the template ref.

Vue

<script setup>
import { ref } from 'vue'
const inputRef = ref(null)

function showValue() {
  alert(inputRef.value.[1])
}
</script>

Drag options to blanks, or click blank then click option'

AinnerHTML

BtextContent

Cvalue

DinnerText

Attempts:

3 left

💡 Hint

Common Mistakes

Using textContent or innerHTML which are for element content, not input value.

For input elements, the property to get the typed text is value.

4fill in blank

hard

Fill both blanks to correctly focus the input element using the template ref.

Vue

<script setup>
import { ref } from 'vue'
const inputRef = ref(null)

function focusInput() {
  inputRef.value.[1]()
}
</script>

<template>
  <input type="text" ref="inputRef" @click="[2]" />
</template>

Drag options to blanks, or click blank then click option'

Afocus

BfocusInput

Cclick

Dblur

Attempts:

3 left

💡 Hint

Common Mistakes

Using click() method instead of focus().

Calling a wrong function name on click event.

The focus() method sets focus on the input element. The @click event calls the focusInput function.

5fill in blank

hard

Fill all three blanks to create a reactive template ref, assign it to the input, and log its value on button click.

Vue

<script setup>
import { [1] } from 'vue'
const inputRef = [2](null)

function logValue() {
  console.log(inputRef.value.[3])
}
</script>

<template>
  <input type="text" ref="inputRef" />
  <button @click="logValue">Log Value</button>
</template>

Drag options to blanks, or click blank then click option'

Aref

Cvalue

Dreactive

Attempts:

3 left

💡 Hint

Common Mistakes

Using reactive instead of ref.

Accessing textContent instead of value.

Use ref to create the template ref and access the input's value property to get the typed text.

Practice

1. What is the main purpose of using template refs in Vue?

easy

A. To directly access DOM elements or child components from the template

B. To define reactive state variables

C. To create computed properties

D. To register global components

Solution

1. Step 1: Understand what template refs do

   Template refs provide a way to directly access DOM elements or child components inside Vue templates.

2. Step 2: Compare with other Vue features

   Reactive state variables and computed properties are for data management, not direct DOM access. Global components registration is unrelated.

3. Final Answer:

   To directly access DOM elements or child components from the template -> Option A

4. Quick Check:

   Template refs = direct DOM/component access [OK]

Hint: Template refs connect template elements to script variables [OK]

Common Mistakes:

• Confusing refs with reactive state
• Thinking refs create computed properties
• Assuming refs register components

2. Which of the following is the correct way to declare a template ref in Vue 3's <script setup> syntax?

easy

A. const myRef = ref(null);

B. let myRef = reactive(null);

C. const myRef = computed(() => null);

D. var myRef = ref('element');

Solution

1. Step 1: Recall how to declare refs in Vue 3 script setup

   Use const myRef = ref(null); to create a ref variable initialized to null.

2. Step 2: Check other options for correctness

   reactive is for objects, not refs. computed is for derived values. Using var is discouraged and 'element' is not a valid initial value for a ref to DOM.

3. Final Answer:

   const myRef = ref(null); -> Option A

4. Quick Check:

   Declare ref with ref(null) [OK]

Hint: Use ref(null) to declare template refs in script setup [OK]

Common Mistakes:

• Using reactive instead of ref for DOM refs
• Initializing ref with wrong value
• Using var instead of const

3. Given the following Vue 3 component code, what will be logged when the button is clicked?

<template>
  <input ref="inputRef" />
  <button @click="focusInput">Focus</button>
</template>

<script setup>
import { ref } from 'vue';
const inputRef = ref(null);
function focusInput() {
  console.log(inputRef.value.tagName);
  inputRef.value.focus();
}
</script>

medium

A. undefined will be logged and an error occurs

B. "inputRef" will be logged and the input will get focus

C. "INPUT" will be logged and the input will get focus

D. Nothing will be logged and no focus happens

Solution

1. Step 1: Understand what inputRef.value refers to

   inputRef is a ref to the input DOM element, so inputRef.value is the actual input element.

2. Step 2: Check what tagName returns and focus behavior

   inputRef.value.tagName returns the uppercase tag name "INPUT". Calling focus() sets keyboard focus on the input.

3. Final Answer:

   "INPUT" will be logged and the input will get focus -> Option C

4. Quick Check:

   inputRef.value.tagName = "INPUT" and focus works [OK]

Hint: Ref value holds the DOM element; tagName is uppercase [OK]

Common Mistakes:

• Logging the ref variable name instead of its value
• Forgetting to use .value to access the element
• Assuming tagName is lowercase

4. Identify the error in this Vue 3 code snippet using template refs:

<template>
  <div ref="box">Content</div>
</template>

<script setup>
import { ref } from 'vue';
const box = ref();
console.log(box.value.textContent);
</script>

medium

A. The ref variable 'box' is not initialized with null

B. Accessing box.value.textContent before DOM is mounted causes error

C. The ref attribute should be used as :ref instead of ref

D. Missing import of onMounted to access DOM safely

Solution

1. Step 1: Check ref initialization and usage timing

   box is declared as ref() without initial value, which defaults to undefined. Accessing box.value.textContent immediately runs before DOM is ready.

2. Step 2: Understand Vue lifecycle for DOM refs

   Template refs are assigned after the component mounts. Accessing them too early (during setup) causes box.value to be null or undefined, so textContent access fails.

3. Final Answer:

   Accessing box.value.textContent before DOM is mounted causes error -> Option B

4. Quick Check:

   Access DOM refs only after mount [OK]

Hint: Access refs after mount, not immediately in setup [OK]

Common Mistakes:

• Trying to read ref value before DOM exists
• Not initializing ref with null (less critical)
• Confusing ref attribute syntax

5. You want to create a Vue 3 component that automatically focuses an input element when the component is mounted using template refs. Which code snippet correctly implements this behavior?

hard

A. <template>
<input :ref="inputRef" />
</template>

<script setup>
import { ref, onMounted } from 'vue';
const inputRef = ref(null);
onMounted(() => {
inputRef.focus();
});
</script>

B. <template>
<input ref="inputRef" />
</template>

<script setup>
import { ref } from 'vue';
const inputRef = ref(null);
inputRef.value.focus();
</script>

C. <template>
<input ref="inputRef" />
</template>

<script setup>
import { ref, onMounted } from 'vue';
const inputRef = ref(null);
onMounted(() => {
inputRef.value.focus();
});
inputRef.value.focus();
</script>

D. <template>
<input ref="inputRef" />
</template>

<script setup>
import { ref, onMounted } from 'vue';
const inputRef = ref(null);
onMounted(() => {
inputRef.value.focus();
});
</script>

Solution

1. Step 1: Use onMounted to run code after DOM is ready

   To safely access the input element, focus must be called inside onMounted lifecycle hook.

2. Step 2: Access the DOM element via inputRef.value and call focus()

   inputRef is a ref initialized to null, and inputRef.value holds the DOM element after mount. Calling inputRef.value.focus() sets focus correctly.

3. Final Answer:

   Code snippet C correctly uses onMounted and inputRef.value.focus() -> Option D

4. Quick Check:

   Use onMounted + inputRef.value.focus() [OK]

Hint: Focus input inside onMounted using inputRef.value.focus() [OK]

Common Mistakes:

• Calling focus outside onMounted before DOM ready
• Using :ref instead of ref attribute
• Calling focus on ref instead of ref.value