Setting up TypeScript in Vue project - Quick Revision & Summary

Recall & Review

beginner

What is the first step to add TypeScript support in a new Vue 3 project?

Use the Vue CLI or Vite to create a new project and select TypeScript support during setup. For example, with Vite: run npm create vite@latest my-vue-app -- --template vue-ts.

intermediate

How do you enable TypeScript in an existing Vue 3 project?

Install TypeScript and Vue's TypeScript support packages, then rename .js files to .ts or .vue files with <script lang="ts">. Also, add a tsconfig.json file to configure TypeScript.

beginner

What is the purpose of lang="ts" in Vue single-file components?

It tells Vue and the build tools that the script section uses TypeScript syntax, so it should be compiled accordingly.

intermediate

Why do you need a shims-vue.d.ts file when using TypeScript in Vue?

Because TypeScript doesn't understand .vue files by default, this file declares modules for Vue files so TypeScript can process them without errors.

advanced

What is a common TypeScript configuration option to improve Vue development experience?

Setting strict: true in tsconfig.json helps catch errors early. Also, enabling jsx: preserve if using JSX, and including src/**/*.vue in include.

Which command creates a new Vue 3 project with TypeScript using Vite?

A npm create vite@latest my-app -- --template vue-ts

B vue create my-app --typescript

C npm init vue@latest my-app

D vue add typescript

Option A uses Vite with the Vue TypeScript template, which sets up TypeScript automatically.

In a Vue single-file component, how do you specify the script uses TypeScript?

A <script type="ts">

B <script type="typescript">

C <script lang="typescript">

D <script lang="ts">

The correct syntax is <script lang="ts"> to indicate TypeScript.

What file tells TypeScript how to handle .vue files?

A shims-vue.d.ts

B vue.config.js

C tsconfig.json

D package.json

The shims-vue.d.ts file declares modules for .vue files so TypeScript can understand them.

Which package is essential to install for TypeScript support in Vue 3?

A vue-router

B vuex

C typescript

D eslint

The typescript package is required to enable TypeScript features.

What is a benefit of enabling strict mode in tsconfig.json?

A It disables type checking.

B It helps catch errors early by enforcing stricter type checks.

C It makes the app run faster.

D It automatically converts JavaScript to TypeScript.

Strict mode enforces stricter type rules, helping find bugs early.

Explain the steps to set up TypeScript in a new Vue 3 project using Vite.

Think about project creation, file setup, and TypeScript declarations.

Describe why the shims-vue.d.ts file is important in a Vue TypeScript project.

Consider how TypeScript treats unknown file types.

Practice

1. What is the main benefit of using TypeScript in a Vue project?

easy

A. It helps catch errors early and improves code clarity.

B. It automatically styles your components.

C. It replaces Vue's template syntax with HTML.

D. It removes the need for JavaScript entirely.

Solution

1. Step 1: Understand TypeScript's role

   TypeScript adds static typing to JavaScript, helping catch errors before running code.

2. Step 2: Relate to Vue projects

   Using TypeScript in Vue improves code clarity and reduces runtime bugs.

3. Final Answer:

   It helps catch errors early and improves code clarity. -> Option A

4. Quick Check:

   TypeScript improves code safety = A [OK]

Hint: TypeScript catches errors before running code [OK]

Common Mistakes:

• Thinking TypeScript styles components
• Confusing TypeScript with HTML templates
• Believing TypeScript removes JavaScript

2. Which command is used to create a new Vue project with TypeScript support?

easy

A. vue create project --typescript

B. npm create vue@latest and select TypeScript option

C. npm install vue typescript

D. vue add typescript

Solution

1. Step 1: Identify the official Vue CLI command

   The recommended way is using npm create vue@latest to start a new project.

2. Step 2: Select TypeScript during setup

   During the interactive setup, you choose TypeScript to enable it.

3. Final Answer:

   npm create vue@latest and select TypeScript option -> Option B

4. Quick Check:

   Use npm create vue@latest for new Vue projects [OK]

Hint: Use npm create vue@latest and pick TypeScript [OK]

Common Mistakes:

• Using old vue CLI commands
• Trying to install TypeScript separately after project creation
• Confusing add commands with create commands

3. Given this Vue component script tag, what is missing to enable TypeScript?

<script>
export default {
  data() {
    return { count: 0 }
  }
}
</script>

medium

A. Wrap the export in a defineComponent call

B. Change data() to setup()

C. Add type="module" to the <script> tag

D. Add lang="ts" attribute to the <script> tag

Solution

1. Step 1: Identify how to enable TypeScript in Vue scripts

   Vue requires lang="ts" on the <script> tag to treat it as TypeScript.

2. Step 2: Check other options

   Changing to setup() or adding type="module" does not enable TypeScript automatically.

3. Final Answer:

   Add lang="ts" attribute to the <script> tag -> Option D

4. Quick Check:

   Use lang="ts" to enable TypeScript [OK]

Hint: Add lang="ts" to script tag for TypeScript [OK]

Common Mistakes:

• Forgetting lang="ts" on script tag
• Confusing setup() with TypeScript enabling
• Assuming type="module" enables TypeScript

4. You added lang="ts" to your Vue component but get errors about missing types. What is the likely cause?

medium

A. You forgot to create or configure tsconfig.json in the project root.

B. You need to remove lang="ts" to fix errors.

C. Vue does not support TypeScript in single file components.

D. You must rename the file extension to .ts instead of .vue.

Solution

1. Step 1: Understand TypeScript configuration needs

   TypeScript requires a tsconfig.json file to know how to compile and check types.

2. Step 2: Check other options

   Removing lang="ts" disables TypeScript, Vue supports TypeScript in .vue files, and renaming files is not needed.

3. Final Answer:

   You forgot to create or configure tsconfig.json in the project root. -> Option A

4. Quick Check:

   tsconfig.json is required for TypeScript setup [OK]

Hint: Create tsconfig.json to avoid missing type errors [OK]

Common Mistakes:

• Removing lang="ts" instead of fixing config
• Thinking Vue disallows TypeScript in .vue files
• Renaming .vue files to .ts incorrectly

5. You want to use TypeScript in a Vue 3 project with the Composition API. Which setup is correct for the script block?

hard

A. <script lang="js" setup>
import { ref } from 'vue'
const count = ref(0)
</script>

B. <script>
import { ref } from 'vue'
const count = ref(0)
</script>

C. <script lang="ts" setup>
import { ref } from 'vue'
const count = ref(0)
</script>

D. <script lang="ts">
export default {
data() { return { count: 0 } }
}
</script>

Solution

1. Step 1: Identify TypeScript and Composition API usage

   Using lang="ts" setup enables TypeScript and Composition API syntax in Vue 3.

2. Step 2: Check other options

   The version with lang="js" setup uses JavaScript not TypeScript, the plain <script> lacks the lang="ts" attribute, and the one using export default with data() is Options API, not Composition API.

3. Final Answer:

   <script lang="ts" setup> with ref import and usage -> Option C

4. Quick Check:

   Use lang="ts" setup for Composition API with TypeScript [OK]

Hint: Use

Common Mistakes:

• Omitting lang="ts" for TypeScript
• Using lang="js" instead of lang="ts"
• Mixing Options API with Composition API syntax