JSX in Vue components - Mini Project: Build & Apply

JSX in Vue components

📖 Scenario: You are building a simple Vue 3 component that uses JSX syntax to render a greeting message and a list of favorite fruits. JSX lets you write HTML-like code inside JavaScript, making your component code clear and easy to read.

🎯 Goal: Create a Vue 3 component using JSX syntax that displays a greeting and a list of fruits.

📋 What You'll Learn

Use Vue 3 Composition API with <script setup>

Use JSX syntax inside the render function

Display a greeting message inside an <h1> tag

Render a list of fruits inside <ul> with each fruit in an <li>

Use a reactive data array for fruits

💡 Why This Matters

🌍 Real World

JSX in Vue components helps you write UI code that looks like HTML but is fully integrated with JavaScript logic, making it easier to build dynamic interfaces.

💼 Career

Many modern Vue projects use JSX or similar templating techniques. Knowing JSX in Vue helps you work on advanced Vue apps and collaborate with teams using this style.

1

Set up the fruits array

Create a reactive array called fruits with these exact values: 'Apple', 'Banana', 'Cherry' using Vue's ref function.

Vue

// Create a reactive array called fruits with 'Apple', 'Banana', 'Cherry'
// Your code here

Hint

Use import { ref } from 'vue' and then const fruits = ref([...]).

2

Add a greeting message

Create a constant called greeting and set it to the string 'Hello from JSX!'.

Vue

import { ref } from 'vue'

const fruits = ref(['Apple', 'Banana', 'Cherry'])
// Create a constant greeting with 'Hello from JSX!'
// Your code here

Hint

Just write const greeting = 'Hello from JSX!'.

3

Write the render function with JSX

Add a render function that returns JSX. It should render an <h1> with the greeting text and a <ul> with each fruit from fruits.value inside an <li>. Use fruits.value.map((fruit) => <li>{fruit}</li>).

Vue

import { ref } from 'vue'

const fruits = ref(['Apple', 'Banana', 'Cherry'])
const greeting = 'Hello from JSX!'

// Add a render function returning JSX with  and  with fruits
// Your code here

Hint

Write a render function that returns JSX with <h1> and <ul>. Use fruits.value.map to create <li> elements.

4

Export the component

Export the component as default with the render function you created. Use export default { render }.

Vue

import { ref } from 'vue'

const fruits = ref(['Apple', 'Banana', 'Cherry'])
const greeting = 'Hello from JSX!'

function render() {
  return (
    
      {greeting}
      
        {fruits.value.map(fruit => {fruit})}
      
    
  )
}

// Export the component with the render function
// Your code here

Hint

Write export default { render } to export the component.

Practice

1. What is the main purpose of using JSX in Vue components?

easy

A. To write HTML-like code inside JavaScript functions for UI rendering

B. To replace JavaScript with HTML code

C. To write CSS styles directly inside Vue components

D. To create Vue components without any JavaScript

Solution

1. Step 1: Understand JSX role in Vue

   JSX allows writing HTML-like syntax inside JavaScript, making UI code dynamic and easier to manage.

2. Step 2: Compare options

   Only To write HTML-like code inside JavaScript functions for UI rendering correctly describes JSX's purpose. Others confuse JSX with CSS or removing JavaScript.

3. Final Answer:

   To write HTML-like code inside JavaScript functions for UI rendering -> Option A

4. Quick Check:

   JSX = HTML-like code in JS [OK]

Hint: JSX mixes HTML look inside JavaScript functions [OK]

Common Mistakes:

• Thinking JSX replaces JavaScript entirely
• Confusing JSX with CSS styling
• Believing JSX removes the need for Vue components

2. Which of the following is the correct way to return JSX inside the setup() function in Vue 3?

easy

A. return Hello;

B. return function() { Hello };

C. return () => (Hello);

D. return { template: 'Hello' };

Solution

1. Step 1: Recall Vue 3 setup JSX syntax

   In Vue 3, setup() returns a render function, usually an arrow function returning JSX wrapped in parentheses.

2. Step 2: Evaluate options

   return () => (
   Hello); correctly returns an arrow function with JSX. return

   Hello

   ; returns JSX directly (invalid). return function() {

   Hello

   }; returns a function but misses return statement. return { template: '

   Hello

   ' }; uses template string, not JSX.

3. Final Answer:

   return () => (<div>Hello</div>); -> Option C

4. Quick Check:

   setup returns arrow function with JSX [OK]

Hint: Always return an arrow function wrapping JSX in setup() [OK]

Common Mistakes:

• Returning JSX directly without a function
• Using function without return statement
• Confusing JSX with template strings

3. What will be the rendered output of this Vue JSX component?

import { defineComponent } from 'vue';
export default defineComponent({
  setup() {
    const name = 'Vue';
    return () => (
      

        
Hello, {name}!
      
    );
  }
});

medium

A. Hello, Vue!

B. Hello, {name}!

C. Hello, !

D. SyntaxError due to JSX expression

Solution

1. Step 1: Understand JSX expression interpolation

   In JSX, curly braces insert JavaScript expressions. Here, {name} inserts the string 'Vue'.

2. Step 2: Predict rendered HTML

   The component renders a div with an h1 containing 'Hello, Vue!'. No syntax errors occur.

3. Final Answer:

   <div><h1>Hello, Vue!</h1></div> -> Option A

4. Quick Check:

   JSX {name} inserts variable value [OK]

Hint: JSX curly braces insert JavaScript values directly [OK]

Common Mistakes:

• Thinking JSX shows variable name literally
• Expecting empty output if variable used
• Assuming JSX causes syntax errors without Babel

4. Identify the error in this Vue JSX component code:

import { defineComponent } from 'vue';
export default defineComponent({
  setup() {
    const count = 0;
    return () => {
      {count}
    };
  }
});

medium

A. count variable should be reactive

B. JSX cannot be used inside setup()

C. setup() should not return a function

D. Missing parentheses around JSX in return function

Solution

1. Step 1: Check JSX return syntax in arrow function

   The arrow function uses curly braces but does not return JSX explicitly or wrap JSX in parentheses, causing no output.

2. Step 2: Correct syntax for returning JSX

   JSX must be wrapped in parentheses and returned explicitly, e.g., () => ( <button>{count}</button> ).

3. Final Answer:

   Missing parentheses around JSX in return function -> Option D

4. Quick Check:

   JSX must be wrapped in parentheses and returned [OK]

Hint: Wrap JSX in parentheses when returning from arrow function [OK]

Common Mistakes:

• Forgetting to return JSX explicitly
• Not wrapping JSX in parentheses
• Thinking reactive is required for static display

5. You want to create a Vue JSX component that renders a list of items passed as a prop. Which is the correct way to map the items array to JSX elements inside setup()?

hard

A. return () => ({props.items.forEach(item => {item})});

B. return () => ({props.items.map(item => {item})});

C. return () => ({for (const item of props.items) {item}});

D. return () => ({props.items.map(item => '' + item + '')});

Solution

1. Step 1: Understand how to render lists in JSX

   JSX uses JavaScript expressions. map() returns an array of JSX elements, perfect for rendering lists.

2. Step 2: Evaluate each option

   return () => (
   {props.items.map(item =>
   • {item}
   )}
   ); correctly uses map() to return
3. elements. return () => (
   {props.items.forEach(item =>
   • {item}
   )}
   ); uses forEach which returns undefined. return () => (
   {for (const item of props.items)
   • {item}
   }
   ); uses invalid syntax inside JSX. return () => (
   {props.items.map(item => '
   • ' + item + '
   ')}
   ); returns strings, not JSX elements.

4. Final Answer:

   return () => (<ul>{props.items.map(item => <li>{item}</li>)}); -> Option B

5. Quick Check:

   Use map() to return JSX list items [OK]

Hint: Use map() to create JSX elements for lists [OK]

Common Mistakes:

• Using forEach instead of map for JSX lists
• Trying to use for loops inside JSX expressions
• Returning strings instead of JSX elements