@vueschool_io

vueschool.io

Vue 2  

New Features and Migrating

3

🎤

@danielkelly_io

@danielkellyio

Alabama, USA

Daniel Kelly

Lead Instructor @ Vue School

Full Stack developer (10 years)

Husband and Father

Workshop Overview

  • Intro to Vue 3
  • Benefits of Vue 3
  • Improvements to Existing Features
  • Removed Features
  • New Features
    • Composition API (overview)*
    • Teleport
    • State Driven CSS*
    • Other CSS Enhancements
    • Emits Declaration
    • Suspense
  • Changes in the Ecosystem
  • Migration

* backported to Vue 2.7

Intro to Vue 3

👋

Pinia Experiment Begins

Nov, 2019

RFC Repo Created

Jan 14, 2019

Vue 3 Codebase Goes Public

Jan 3, 2020

Vue 3 Soft Launch
(One Piece)

Sep 18, 2020

Vue 3 New Default

Jan 20, 2022

Evan Announced Dev on Vite.js

Jan 12, 2020

📣

Vue 3 Development Announced

Feb 2018

v3

Volar

<script setup>

more!

Why Vue 3?

Benefits and why upgrade

Smaller and Faster

  • Initial render up to 55% faster
  • Memory usage down 54%
  • Updates up to 133% faster
  • Unused features are tree-shakeable (like transitions, nextTick, etc)

Faster === better conversions

A one-second site speed improvement can increase mobile conversions by up to 27%.

===

Write More Maintainable Code

  • Better logic re-use and organization with the Composition API *
  • Type-safety with improved TypeScript Support
    (TypeScript is fast becoming the norm for large scale JavaScript apps)
  • Other new features and API adjustments that make code more intuitive

* backported to Vue 2.7

More Maintainable Code is Good For Everyone!

✅ Stakeholders
       Faster turn around times, less back and forth

✅ Site Visitors/Customers
       Less bugs, more features faster

✅ Developers

       Better DX, Iterate faster, spend less time debugging

Supported by the Latest and Greatest Libraries

  • Some of the newest 3rd party plugins, frameworks, etc only support Vue 3
  • ie. FormKit, Nuxt 3, Vuetify 3, etc

Much of the Same Syntax We Already Love ❤️

  • Options API Still 100% Supported
  • Single File Components
    (script, template, style)
  • Declarative Template Syntax

Vue 2 EOL is Dec 2023

Improvements to Existing Features

Improvements to Existing Features

  • Multiple v-models (and more!)
  • No more reactivity caveats 🎉
  • Fragments
  • Comprehensive $attrs

Multiple v-models

// MyInput.vue
<template>
<input 
  @input="$emit('input', $event.target.value)" 
  :value="value" 
/>
</template>
<script>
export default {
  props:{
    value: String
  }
}
</script>

Support v-model on a component by emitting input and accepting a value prop

v2

<MyInput v-model="name" />

Multiple v-models

// MyInput.vue
<template>
<input 
  @input="$emit('update:modelValue', $event.target.value)" 
  :value="modelValue" 
/>
</template>
<script>
export default {
  props:{
    modelValue: String
  }
}
</script>

Support v-model on a component by emitting update:modelValue and accepting a modelValue prop

v3

<MyInput v-model="name" />

Multiple v-models

// MyInput.vue
<template>
<input 
  @input="$emit('update:modelValue', $event.target.value)" 
  :value="modelValue" 
/>
<input 
  @input="$emit('update:email', $event.target.value)" 
  :value="title" 
/>
  <input 
  @input="$emit('update:password', $event.target.value)" 
  :value="title" 
/>
</template>
<script>
export default {
  props:{
    modelValue: String,
    email: String,
    password: String,
  }
}
</script>

Provide argument to v-model to specify any prop/update:[prop]

v3

<MyInput 
  v-model="name" 
  v-model:email="email"
  v-model:password="password"
/>

Multiple v-models

<MyComponent 
  :title="pageTitle" 
  @update:title="pageTitle = $event" 
/>

<!-- Shortand for Above -->
<MyComponent :title.sync="pageTitle" />

Multiple v-models replace .sync

v2

Multiple v-models

<MyComponent 
  :title="pageTitle" 
  @update:title="pageTitle = $event" 
/>

<!-- Shortand for Above -->
<MyComponent v-model:title="pageTitle" />

Multiple v-models replace .sync

v3

v-model anatomy

Custom v-model modifiers

<MyComponent v-model.capitalize="myText" />

Vue 3 also allows us to create custom modifiers for v-model

Custom v-model modifiers

<!-- MyComponent.vue-->
<script>
export default {
  props: {
    //...
    modelModifiers: {
      default: () => ({})
    }
  },
  created() {
    console.log(this.modelModifiers) // { capitalize: true }
  }
  //...
}
</script>

Check for them on the modelModifiers prop. Added modifiers will be a boolean true

<MyComponent v-model.capitalize="myText" />

Custom v-model modifiers

<!-- MyComponent.vue-->
<script>
export default {
  //... 
  methods: {
    emitValue(e) {
      let value = e.target.value
      if (this.modelModifiers.capitalize) {
        value = value.charAt(0).toUpperCase() + value.slice(1)
      }
      this.$emit('update:modelValue', value)
    }
  }
}
</script>

Then you can alter the emitted value based on the modifier

No More Reactivity Caveats

         Vue.set(this.frameworks, index, 'Vue')

v2

 this.frameworks[index] = "Vue"

v3

Setting a new array item

No More Reactivity Caveats

         Vue.set(this.framework, 'name', 'Vue')

v2

 this.framework.name = "Vue"

v3

Adding a new object property

No More Reactivity Caveats

         Vue.delete(this.framework, 'caveats')

v2

 delete this.framework.caveats

v3

Deleting an object property

No More Reactivity Caveats

Less Caveats === More Intuitive === Less Bugs

Fragments

aka. Multiple Root Elements

v2

<template>
  <div>...</div>
  <div>...</div>
</template>

❌

If you did this...

Fragments

aka. Multiple Root Elements

v2

<template>
  <div>...</div>
  <div>...</div>
</template>

You'd get an error like this!

Fragments

aka. Multiple Root Elements

v2

<template>
<div>
  <div>...</div>
  <div>...</div>
</div>
</template>

And have to wrap everything with a div

(which sometimes causes styling issues)

Fragments

aka. Multiple Root Elements

v3

<template>
  <div>...</div>
  <div>...</div>
</template>

It's no problem! 🎉

Fragments

aka. Multiple Root Elements

v3

<template>
  <div>...</div>
  <div v-bind="$attrs">...</div>
</template>

And you can specify where to put the fall-through attributes

Comprehensive $attrs

v2

<template>
  <label>
    <input type="text" v-bind="$attrs" v-on="$listeners" />
  </label>
</template>
<script>
  export default {
    inheritAttrs: false
  }
</script>

Listeners separate from $attrs and if you wanted them to fall through you must remember to bind seperately

Comprehensive $attrs

v3

//MyInput.vue

<template>
  <label>
    <input type="text" v-bind="$attrs" />
  </label>
</template>
<script>
export default {
  inheritAttrs: false
}
</script>

Listeners combined with $attrs. Defined as functions prefixed with on

<MyInput id='my-input' @close="..."/>

$attrs === {
  id: 'my-input',
  onClose(){
    ...
  }
}

Comprehensive $attrs

v2

// MyInput.vue
<template>
  <label>
    <input type="text" v-bind="$attrs" />
  </label>
</template>
<script>
export default {
  inheritAttrs: false
}
</script>

Class and Style separate from $attrs

Given this component definition...

Comprehensive $attrs

v2

<MyInput id="my-id" class="my-class" />

Class and Style separate from $attrs

And used like this...

<label class="my-class">
  <input type="text" id="my-id" />
</label>

Would render this HTML

Comprehensive $attrs

v3

<MyInput id="my-id" class="my-class" />

Class and Style included with $attrs

And used like this...

<label>
  <input type="text" id="my-id" class="my-class" />
</label>

Would render this HTML

Questions?

🙋🏾‍♀️

Assignment # 1

👩‍💻👨🏽‍💻

⏰ 20 mins

❌ Removed Features

❌ Removed Features

  • Functional Components
  • Filters
  • Keycode Modifiers
  • $children

Functional Components

<template functional>
  <component 
    :is="`h${props.level}`" 
    v-bind="attrs" 
    v-on="listeners"
  >
    <slot></slot>
  </component>
</template>

<script>
export default {
  props: ["level"],
};
</script>

v2

In v2, functional components provided a more performant alternative when component state was not needed

No $ prefix

Functional Components

<template>
  <component 
    :is="`h${props.level}`" 
    v-bind="$attrs" 
  >
    <slot></slot>
  </component>
</template>

<script>
export default {
  props: ["level"],
};
</script>

v3

In v3, the performance difference for stateful components is negligible so functional SFC's are removed

$ prefix

No functional

keyword

Functional Components

<script>
// note that h is imported from vue 
// instead of provided as an argument to the render function 
// (another diff between v2 and v3)
import { h } from "vue"; 

// functional components is a render function
const DynamicHeading = (props, context) => {
  return h(`h${props.level}`, context.attrs, context.slots);
};

DynamicHeading.props = ["level"];

export default DynamicHeading;
</script>

v3

Or you can define functional components as plain functions

 

Filters

<template>
  <h1>Bank Account Balance</h1>
  <p>{{ accountBalance | currencyUSD }}</p>
</template>

<script>
  export default {
    //...
    filters: {
      currencyUSD(value) {
        return '$' + value
      }
    }
  }
</script>

v2

In v2, you could use filters to format data in the template

 

Custom syntax that involves:

  • a learning curve
  • and implementation costs

Filters

<template>
  <h1>Bank Account Balance</h1>
  <p>{{ accountInUSD }}</p>
</template>

<script>
  export default {
    //...
    computed: {
      accountInUSD() {
        return '$' + this.accountBalance
      }
    }
  }
</script>

v3

In v3, filters are removed. Just use a computed prop instead.

 

Global Filters

const app = createApp(App)

app.config.globalProperties.$filters = {
  currencyUSD(value) {
    return '$' + value
  }
}

v3

In v3, global filters can be replaced with globally defined methods

 

<template>
  <h1>Bank Account Balance</h1>
  <p>{{ $filters.currencyUSD(accountBalance) }}</p>
</template>

KeyCode Modifiers

v2

In Vue 2 you could use keycodes as modifiers for keyboard events

 


<!-- keycode 75 === 'k' -->
<input v-on:keyup.75="doThing" />

KeyCode Modifiers

v3

In Vue 3 you use the event's key value instead



<input v-on:keyup.k="doThing" />


<input v-on:keyup.k="doThing" />

KeyCode Modifiers

v3

For multi-word key names you'll use the kebab case



<input v-on:keyup.arrow-down="doThing" />

KeyCode Modifiers

v3

The keys for some punctuation marks can just be included literally.

(This excludes ", ', /, =, >, and . You can check these on the event in your handler)



<input v-on:keyup.,="commaPress" />

KeyCode Modifiers

KeyboardEvent.keyCode is now deprecated in browsers and no longer recommended for use. Therefore Vue 3 removes them.

 



<input v-on:keyup.k="doThing" />

developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/keyCode

$children

v2

<template>
  <div>
    <my-button>Change logo</my-button>
  </div>
</template>

<script>
import MyButton from './MyButton'

export default {
  components: { MyButton },
  mounted() {
    console.log(this.$children[0]) // VueComponent (MyButton)
  }
}
</script>

In Vue 2, you could access all a components child components via $children

 

$children

v3

In Vue 3, $children no longer exists. If you need access to a component via the parent you can use a template ref instead

 

<template>
  <div>
    <my-button ref="button">Change logo</my-button>
  </div>
</template>

<script>
import MyButton from './MyButton'

export default {
  components: { MyButton },
  mounted() {
    console.log(this.$refs.button) // VueComponent (MyButton)
  }
}
</script>

Questions?

🙋🏾‍♀️

Assignment #2&3

👩‍💻👨🏽‍💻

⏰ 15 mins

Assignment #2&3

👩‍💻👨🏽‍💻

⏰ 15 mins

Skip

10 Minute Break

☕️🙆

⏰ 10 mins

🎉 New Features

🎉 New Features

  • Composition API *
  • Teleport
  • State Driven CSS *
  • Other CSS Enhancements
  • Emits Declaration
  • Suspense

* backported to Vue 2.7

Composition API

Code Organization

Logic Reuse

Improved

TypeScript Support

Composition API

Full Workshop Dedicated to CAPI

Composition API

⚡️ Super Quick Overview

new Vue({
  data(){
    return {
      loading: false,
      count: 0,
      user: {}
    }
  },
  computed: {
    double () { return this.count * 2 },
    fullname () {/* ... */}
  },
  methods: {
    increment () { this.count++ },
    fetchUser () {/* ... */}
  }
})
import { ref, computed, watch } from 'vue'

No longer passing options INTO Vue

Instead we're getting reactive functions OUT OF Vue

const loading = ref(false)
const count = ref(0)
const user = reactive({})
new Vue({
  data(){
    return {
      loading: false,
      count: 0,
      user: {}
    }
  },
  computed: {
    double () { return this.count * 2 },
    fullname () {/* ... */}
  },
  methods: {
    increment () { this.count++ },
    fetchUser () {/* ... */}
  }
})

Define reactive data with

ref

or

reactive

const double = computed(()=> count.value * 2)
const fullname = computed(()=>({ /* ... */ }))
new Vue({
  data(){
    return {
      loading: false,
      count: 0,
      user: {}
    }
  },
  computed: {
    double () { return this.count * 2 },
    fullname () {/* ... */}
  },
  methods: {
    increment () { this.count++ },
    fetchUser () {/* ... */}
  }
})

Define derived data with

computed

const increment = ()=> count.value++
function fetchUser(){ /* ... */ }
new Vue({
  data(){
    return {
      loading: false,
      count: 0,
      user: {}
    }
  },
  computed: {
    double () { return this.count * 2 },
    fullname () {/* ... */}
  },
  methods: {
    increment () { this.count++ },
    fetchUser () {/* ... */}
  }
})

Define methods as

functions

Composition API

Full Workshop Dedicated to CAPI

You seem like a pretty advanced audience

Do you have any specific questions about the composition API?

Would you like to dive a little deeper into the Composition API?

(I can show you some examples in StackBlitz)

🤫

Don't tell anyone but I'll give you the content and exercises from our dedicated Composition API workshop too!

(copy and paste into chat)

Teleport

  • Allows us to keep markup inside a component but visually display it elsewhere in the DOM
  • Great for modal overlays

Teleport

Modal overlay without teleport usually relies on fixed positioning

<template>
  <button @click="open = true">Open Modal</button>

  <div v-if="open" class="modal">
    <slot></slot>
    <footer>
      <button @click="open = false">Close</button>
    </footer>
  </div>
</template>

<script>
  // ....
</script>

<style scoped>
.modal {
  @apply fixed;
}
</style>
  • Position fixed only works if an ancestor doesn't include `transform`, `perspective`, or `filter`
  • z-index issues

v2

Teleport

Append markup to any arbitrary element no matter where the component lives

<template>
  <button @click="open = true">Open Modal</button>

  <Teleport to="body">
    <div v-if="open" class="modal">
      <slot></slot>
      <footer>
        <button @click="open = false">Close</button>
      </footer>
    </div>
  </Teleport>
</template>

<script>
  // ....
</script>

<style scoped>
.modal {
  @apply absolute;
}
</style>

v3

Teleport Tips

`to` prop takes a CSS selector or an actual DOM node

<template>
   <!-- string query selector-->
  <Teleport to="body">
    <!--or actual element-->
  <Teleport :to="body">
</template>

<script>
export default {
  data() {
    return {
      body: document.querySelector("body"),
    };
  },
};
</script>

Teleport Tips

can combine <Teleport> with <Transition>

<template>
   <Teleport :to="body">
    <Transition>
      <div v-if="open" class="modal">
        //...
      </div>
    </Transition>
  </Teleport>
</template>
<style scoped>
.v-enter-active,
.v-leave-active {
  transition: opacity 0.5s ease;
}

.v-enter-from,
.v-leave-to {
  opacity: 0;
}
</style>

Teleport Tips

Can have multiple teleports active at one time.

<Teleport to="#modals">
  <div>A</div>
</Teleport>
<Teleport to="#modals">
  <div>B</div>
</Teleport>
<div id="modals">
  <div>A</div>
  <div>B</div>
</div>

Teleport Tips

Can dynamically disable. Useful to conditionally display inside component

<Teleport :disabled="isMobile">
  ...
</Teleport>

Teleport Tips

 The teleport `to` target must already exist in the DOM when the component using <Teleport> is mounted.

  • Ideally, this is an element outside the Vue app.
  • When targeting elements rendered by Vue, ensure it's mounted first

Questions?

🙋🏾‍♀️

Assignment #4

👩‍💻👨🏽‍💻

⏰ 25 mins

Lunch

🍔

⏰ 25 mins

Lunch Break

🍽️

⏰ 25 mins

State Driven CSS

and more!

State Driven CSS

In v2, inline styles were the only option for dynamic CSS rules

<template>
<div 
  class="swatch"
  :style="{ backgroundColor: color }"
></div>
</template>
<script>
export default{
  data(){
    return {
      color: "red"
    }
  }
}
</script>

v2

State Driven CSS

Re-use would mean re-declaring the inline style

<template>
<div 
  class="swatch"
  :style="{ backgroundColor: color }"
></div>
  
<div 
  class="swatch"
  :style="{ backgroundColor: color }"
></div>
</template>
<script>
export default{
  data(){
    return {
      color: "red"
    }
  }
}
</script>

v2

State Driven CSS

In v3, you can bind CSS values directly in the style block

v3

<template>
<div>
  <div class="swatch"></div>
  <div class="swatch"></div>
</div>
</template>
<script>
export default{
  data(){
    return { color: "red" }
  }
}
</script>

<style scoped>
  .swatch{
    background-color: v-bind(color);
  }
</style>

State Driven CSS

Defines a hashed CSS custom property on the root component element

(or on each element if no root)

v3

<template>
<div>
  <div class="swatch"></div>
  <div class="swatch"></div>
</div>
</template>
<script>
export default{
  data(){
    return { color: "red" }
  }
}
</script>

<style scoped>
  .swatch{
    background-color: v-bind(color);
  }
</style>

State Driven CSS

Can use dot notation to target nested data (must use quotes)

v3

<template>
<div class="swatch"></div>
<div class="swatch"></div>
</template>
<script>
export default{
  data(){
    return {
      colors:{ primary: "red" }
    }
  }
}
</script>

<style scoped>
  .swatch{
    background-color: v-bind('color.primary');
  }
</style>

State Driven CSS

v-bind must the entire value

v3

<template>
<div class="swatch"></div>
<div class="swatch"></div>
</template>
<script>
export default{
  data(){
    return {
      colors:{ primary: "red" },
      width: 100
    }
  },
  computed:{
    widthInPixels(){ return this.width + 'px'}
  }
}
</script>

<style scoped>
  .swatch{
    background-color: v-bind('color.primary');
    width: v-bind(width)px; /* ❌ This won't work */
    width: v-bind(widthInPixels);
  }
</style>

Vue Specific CSS Selectors

v3

<style scoped>
/* Style child components */
.a :deep(.b) {}
  
/* Style slot content */
:slotted(div) {}  

/* Quickly define a global rule */
:global(.red) {}
</style>

<style>
/* Same as :global in scoped tag above */
.red{}
</style>

Questions?

🙋🏾‍♀️

Assignment #5

👩‍💻👨🏽‍💻

⏰ 15 mins

Emits Option

Declare Component Events

Emits Option

Emits scattered throughout component

<!-- DataSender.vue -->
<template>
  <div>
    <button @click="sendData">Send Data</button>
  </div>
</template>

<script>
export default {
  methods: {
    sendData() {
      this.$emit('sending-start')
      
      // send data to API

      this.$emit('sending-complete')
    }
  }
}
</script>

v2

Emits Option

Declare all events with emits option

<!-- DataSender.vue -->
<template>
  <div>
    <button @click="sendData">Send Data</button>
  </div>
</template>

<script>
export default {
  emits:['sending-start', 'sending-complete'],
  methods: {
    sendData() {
      this.$emit('sending-start')
      
      // send data to API

      this.$emit('sending-complete')
    }
  }
}
</script>

v3

Emits Option

Benefits of Emit Option

  • It documents component events in a single place
<script>
export default {
  emits:['sending-start', 'sending-complete'],
  //...
}
</script>

Important for devs and tooling

Emits Option

Benefits of Emit Option

  • When using TypeScript events appear in intellisense results

Emits Option

Benefits of Emit Option

  • Makes the removal of $listeners possible
  • Why? because listeners for declared events are removed from the `$attrs`
  • This also makes means no more .native
<MyButton @click.native="doThing" />

Emits Option

Benefits of Emit Option

  • Documents component events in a single place
  • When using TypeScript events appear in intellisense results



     
  • Listeners for declared events are removed from the `$attrs`
  • Can validate emit payload

Emits Option

Validate event payload

<!-- DataSender.vue -->
<!--...-->
<script>
export default {
  // define as object to use validation
  emits:{
    // null is no validation
    'sending-start': null,
    
    // or provide function to validate
    // return truthy for valid, falsy for invalid
    'sending-complete'(payload){
      return !!(typeof payload.duration === 'number' && payload.response);
    }
  },
  methods: {
    sendData() {
      this.$emit('sending-start')
      
      // send data to API

      this.$emit('sending-complete', {
        duration: 2,
        // response: 'how are you'
      })
    }
  }
}
</script>

v3

Emits Option

Validate event payload with TypeScript

<script lang="ts">
import { defineComponent } from 'vue'

export default defineComponent({
  emits: {
    addBook(payload: { bookName: string }) {
      // perform runtime validation
      return payload.bookName.length > 0
    }
  },
  methods: {
    onSubmit() {
      this.$emit('addBook', {
        bookName: 123 // Type error!
      })

      this.$emit('non-declared-event') // Type error!
    }
  }
})
</script>

v3

Questions?

🙋🏾‍♀️

Assignment #6

👩‍💻👨🏽‍💻

⏰ 20 mins

Assignment #6

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⏰ 20 mins

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Suspense

What is Suspense?

Admittedly a little difficult to understand if you've never heard of it before

Suspense

Orchestrate async dependencies

Without Suspense

With Suspense

With Suspense

 

(with more control at component level)

AKA - eliminate popcorn loading

Suspense

In Vue 2 you'd have local loading data in
the component

<!-- PostsList.vue -->
<script>
export default{
  data(){
    return {
      loading: true,
      posts: null
    }
  },
  async created(){
    const res = await fetch("https://myapi.com/posts")
    this.posts = await res.json()
    this.loading = false
  }
}
</script>
<template>
<div>
  <AppSpinner v-if="loading"/>
  <div v-else>...</div>
</div>
</template>

v2

Suspense

Somewhere higher in the higharchy would use the component and others like it

<!-- ParentComponent.vue -->
<template>
<div>
  <PostsList />
  <UsersList />
  <CommentsList />
</div>
</template>

v2

Suspense

Let's take the same component and

modify it for Vue 3

<!-- PostsList.vue -->
<script>
export default{
  data(){
    return {
      loading: true,
      posts: null
    }
  },
  async created(){
    const res = await fetch("https://myapi.com/posts")
    this.posts = await res.json()
    this.loading = false
  }
}
</script>
<template>
<div>
  <AppSpinner v-if="loading"/>
  <div v-else>...</div>
</div>
</template>

v2

Suspense

In Vue 3 you can get rid of all that loading state in the component

<!-- PostsList.vue -->
<script>
export default{
  data(){
    return {
      posts: null
    }
  },
  async created(){
    const res = await fetch("https://myapi.com/posts")
    this.posts = await res.json()
  }
}
</script>
<template>
<div>
  <div>...</div>
</div>
</template>

v3

Suspense

Then return an async setup function
instead

<!-- PostsList.vue -->
<script>
export default{
  async setup(){
    const res = await fetch("https://myapi.com/posts")
    const posts = await res.json()
    return { posts }
  },
}
</script>
<template>
<div>
  <div>...</div>
</div>
</template>

v3

Don't worry too much about how setup works right now

Suspense

With script setup you can use a top level await

<!-- PostsList.vue -->
<script setup>
const res = await fetch("https://myapi.com/posts")
const posts = await res.json()
</script>
<template>
<div>
  <div>...</div>
</div>
</template>

v3

Don't worry too much about how setup works right now

Suspense

Then in the parent you use suspense to show a

single loader once all promises have resolved

<!-- ParentComponent.vue -->
<template>
<div>
  <Suspense>
    <!-- Put all the async components 
         inside the default slot -->
    <template #default>
      <PostsList />
      <UsersList />
      <CommentsList />
    </template>
    
    <!-- And your loader 
         in the fallback slot -->
    <template #fallback>
      <AppSpinner/>
    </template>
  </Suspense>
</div>
</template>

v3

Suspense

Also works with asyncComponents

(different chunk from main js bundle)

<script>
import { defineAsyncComponent } from 'vue'

export default {
  components: {
    AdminPage: defineAsyncComponent(() =>
      import('./components/AdminPageComponent.vue')
    )
  }
}
</script>

<template>
  <Suspense>
    <template #default> <AdminPage /> </template>
    <template #fallback> <AppSpinner/> </template>
  </Suspense>
</template>

v3

Suspense

Total control by mixing async setup and local loading state

<!-- ParentComponent.vue -->
<template>
<div>
  <Suspense>

    <template #default>
      <!-- has async setup -->
      <PostsList /> 
      <!-- has async setup -->
      <UsersList /> 
      <!-- handles own loading state -->
      <CommentsList /> 
    </template>
    
    <template #fallback>
      <AppSpinner/>
    </template>
  </Suspense>
</div>
</template>

v3

Suspense

Does it do error handling?

Suspense Recap

  • Eliminates "Popcorn loading"
  • Less boilerplate in components (no loading state)
  • Handle loading state at top level
  • Can still handle loading state in component if desired for total control

Suspense Word of Warning

Suspense is technically an experimental feature

vuejs.org/guide/built-ins/suspense.html

Suspense Word of Warning

But Nuxt 3 uses in production... so I wouldn't

worry about Vue.js core making breaking changes

nuxt.com/docs/api/composables/use-async-data#params

Questions?

🙋🏾‍♀️

Assignment #7

👩‍💻👨🏽‍💻

⏰ 20 mins

5 Minute Break

☕️🙆

⏰ 5 mins

Migrate to Vue 3

Why Migrate to Vue 3

  • All the great new features we've already talked about! 
  • (Many of these are back-ported to 2.7^)
  • Get continued support and updates (security patches, future new features, etc)

What if I can't migrate?

Never Ending Vue 2 Support from HeroDevs

How do I Migrate to V3?

https://v3-migration.vuejs.org/

How do I Migrate to V3?

The Official Migration guide provides:

  • A list of breaking changes complete with examples of prior behavior, new behavior, and a strategy for migrating

Breaking Changes

Example of Filter

Notable Breaking Changes

Besides the breaking changes already seen throughout the workshop, there are a few more worthy of noting

🔖

Notable Breaking Changes

Async compnent syntax changed

<!-- Vue 2 -->
<script>
export default{
  components:{
    MyAsyncComponent: () => import('./MyAsyncComponent.vue')
  }
}
</script>

<!-- Vue 3 -->
<script>
import {defineAsyncComponent} from "vue"
export default{
  components:{
    MyAsyncComponent: defineAsyncComponent(
      () => import('./MyAsyncComponent.vue')
    )
  }
}
</script>

Watch on Arrays

<script>
export default{
  data(){
    return {
      food: ['Hamburger', 'Hotdog', 'Spaghetti', 'Taco']
    }
  },
  watch:{
    // Vue 2 - will fire when array replaced, order changed, item added, etc
    // Vue 3 - will only fire when array is replaced
    food(){
      console.log('food changed')
    },
    
    // Vue 3 - must provide for handler to fire on order changed, item added, etc
    food:{
      handler(){
        console.log('food changed')
      },
      deep: true
    }
  }
}
</script>

Notable Breaking Changes

Global API Treeshaking

<!-- Vue 2 -->
<script>
import Vue from 'vue'

Vue.nextTick(() => {
  // something DOM-related
})
</script>

<!-- Vue 3 -->
<script>
import { nextTick } from 'vue'

nextTick(() => {
  // something DOM-related
})
</script>

Notable Breaking Changes

Global API Treeshaking

<!-- Vue 2 -->
<script>
import Vue from 'vue'

Vue.nextTick(() => {
  // something DOM-related
})
</script>

<!-- Vue 3 -->
<script>
import { nextTick } from 'vue'

nextTick(() => {
  // something DOM-related
})
</script>

Notable Breaking Changes

Also Vue.version

<!-- Vue 2 -->
<script>
import Vue from 'vue'
console.log(Vue.version)
</script>

<!-- Vue 3 -->
<script>
import { version } from 'vue'
console.log(version)
</script>

Custom Directives Hooks

// Vue 2
Vue.directive('highlight', {
  bind(el, binding, vnode) {
    el.style.background = binding.value
  }
})

// Vue 3
const app = Vue.createApp({})

app.directive('highlight', {
  beforeMount(el, binding, vnode) {
    el.style.background = binding.value
  }
})

Notable Breaking Changes

custom directive hooks mirrors component lifecycle hooks

Custom Directives Hooks

Notable Breaking Changes

  • created - new! This is called before the element's attributes or event listeners are applied.
  • bind → beforeMount
  • inserted → mounted
  • beforeUpdate: new! This is called before the element itself is updated, much like the component lifecycle hooks.
  • update → removed! There were too many similarities to updated, so this is redundant. Please use updated instead.
  • componentUpdated → updated
  • beforeUnmount: new! Similar to component lifecycle hooks, this will be called right before an element is unmounted.
  • unbind -> unmounted

Notable Breaking Changes

All breaking changes can be found at:

https://v3-migration.vuejs.org/breaking-changes/

How do I Migrate to V3?

 

  • A list of breaking changes complete with examples of prior behavior, new behavior, and a strategy for migrating
  • A list of New Framework-level Recommendations

The Official Migration guide provides:

How do I Migrate to V3?

Vue - Official

New Framework Level Recomendations

  • Vue Core v2 ➡ v3
    ✅ Yes, this is the priority

🟥

🟨

🟨

🟥

  • Options ➡ Composition
    ➡️ Recommend using CAPI going forward as needed
  • Vue CLI ➡ Vite
    🏁 Sooner or later
  • Vuex ➡ Pinia
    🏁 Sooner or later

Difficulty

🟩 Easy

🟨 Medium

🟥 Hard

  • Router, Devtools, test-utils

🟩

🟩

  • Vetur ➡ Volar
    ✅ Yes for VS Code, super easy

Resource for Other Migrations

How do I Migrate to V3?

 

  • A list of breaking changes complete with examples of prior behavior, new behavior, and a strategy for migrating
  • A list of New Framework-level Recommendations
  • Migration build

The Official Migration guide provides:

What is the Migration Build?

  • @vue/compat
  • a build of Vue 3 that supports Vue 2 API's (mostly)
  • Usage of features that have changed or been deprecated in Vue 3 will emit runtime warnings.
  • Used for migrating from Vue 2 to Vue 3

Install Vue 3 and Migration Build

npm install vue@3.2.45
npm install @vue/compat

Step

1

Alias vue to @vue/compat

Step

2

// vue.config.js (vue-cli)
module.exports = {
  chainWebpack: config => {
    config.resolve.alias.set('vue', '@vue/compat')

    config.module
      .rule('vue')
      .use('vue-loader')
      .tap(options => {
        return {
          ...options,
          compilerOptions: {
            compatConfig: {
              MODE: 2
            }
          }
        }
      })
  }
}

Vue Docs also contains example configs for:

  • Plain Webpack
  • Vite

Vue CLI

Handle compile time errors

Step

3

  • Errors will display in the terminal when running `npm run serve`
  • Is recommended to handle all compile time errors first

Handle compile time errors

Step

3

  • Errors will display in the terminal when running `npm run serve`
  • Is recommended to handle all compile time errors first

Set compiler to Vue 3 mode

Step

4

module.exports = {
  //...
  compilerOptions: {
    compatConfig: {
      MODE: 2,
      MODE: 3
    },
  },
}

Means the Vue compiler should expect all compiler level code to be written as per Vue 3 specification

Set compiler to Vue 3 mode

Step

4

module.exports = {
  //...
  compilerOptions: {
    compatConfig: {
      MODE: 2,
      MODE: 3
    },
  },
}

Means the Vue compiler should expect all compiler level code to be written as per Vue 3 specification

More on compatConfig in a minute!

Update dependencies like Vue Router and Vuex

Step

5

Official dependencies will have their own migration guides. Others may or may not. (This is where things can get a little dicey, but the ecosystem has definitely progressed)

Run app and go through console warnings

Step

6

  • Deprecations will show in console
  • Can filter warnings in console to concentrate on one type of change at a time

IDs for warnings found here:

https://v3-migration.vuejs.org/migration-build.html#feature-reference

ID

Explanation

 Link to docs

Run app and go through console warnings

Step

6

  • Once you've handled all instances of a feature ID you can turn compatibility for it off
  • All your tests involving that feature should now pass and be 100% compatible with Vue 3
// main.js
import { configureCompat } from 'vue'

// disable compat for certain features
configureCompat({
  COMPONENT_V_MODEL: false,
  FEATURE_ID_B: false
})

Run app and go through console warnings

Step

6

  • you could also do the same config at the component level
  • Use case for this? 🤷 Maybe you could migrate one component at a time as opposed to one feature ID at a time
export default {
  compatConfig: {
     COMPONENT_V_MODEL: false,
     FEATURE_ID_B: false
  }
  // ...
}

Run app and go through console warnings

Step

6

  • Can deploy to production with partial migration (warnings still in console)
  • Minimal performance hit
  • HOWEVER, I recommend a git branch for complete migration and deploy all together
feature/vue-3-migration

and maybe a commit per feature ID?

Run app and go through console warnings

Step

6

  • when all console warnings are gone you'll end up with a compatConfig that's disabled all applicable feature ID's
  • but you'll have one feature ID left to handle: TRANSITION_CLASSES
configureCompat({
  COMPONENT_V_MODEL: false,
  GLOBAL_MOUNT_CONTAINER: false,
  GLOBAL_MOUNT: false,
  GLOBAL_SET: false,
  //... 
})

Update transition class names (no console warning)

Step

7

  • You can do a project-wide search in IDE for .*-enter and .*-leave CSS class names
     
  • Replace                      with
     
  • Replace                      with
.v-enter
.v-enter-from
.v-leave
.v-leave-from

Update transition class names (no console warning)

Step

7

  • add TRANSITION_CLASSES to compatConfig
configureCompat({
  // ...
  TRANSITION_CLASSES: false
})

Update transition class names (no console warning)

Step

7

  • once all the IDs have had compatibility turned off that's the equivalent of changing the compatConfig.mode to 3
configureCompat({
   MODE: 3
})

Switch to Vue 3 proper

Step

8

  1. uninstall @vue/compat
  2. remove any compat config
  3. remove alias of vue to @vue/compat
// package.json
"@vue/compat": "^3.1.0",


// vue.config.js
module.exports = {
  chainWebpack: (config) => {
    config.resolve.alias.set("vue", "@vue/compat");

    config.module
      .rule("vue")
      .use("vue-loader")
      .tap((options) => {
        return {
          ...options,
          compilerOptions: {
            compatConfig: {
              MODE: 3,
            },
          },
        };
      });
  },
};

import { 
  createApp, 
  configureCompat 
} from "vue";

import App from "./App.vue";

configureCompat({
  COMPONENT_V_MODEL: false,
  GLOBAL_MOUNT_CONTAINER: false,
  GLOBAL_MOUNT: false,
  GLOBAL_SET: false,
  //... 
})

1

2

3

Questions?

🙋🏾‍♀️

HOMEWORK!

👩‍💻👨🏽‍💻

Do you accept this challenge? 💪

Assignment #8

👩‍💻👨🏽‍💻

⏰ 30 mins

Questions?

🙋🏾‍♀️

General Q&A

❓

⏰ 15 minutes

Thank You!

🙏