Vuejs

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Category:JavaScript


title
Vuejs Training Course
author
Lukasz Sokolowski


Vuejs

Vuejs Training Materials

Introduction

  • JavaScript framework for building UI (user interfaces)
  • What do we need?
    • HTML, CSS, and JavaScript
  • Declarative, component-based programming model
    • Declarative rendering
    • Reactivity
  • Progressive framework
  • Single-file components (SFC)
  • API Styles - options VS composition

Not That

NotVue.png

BUT still - we'll have a lot to see! (-'

Framework

Progressive Framework - "framework that can grow with you and adapt to your needs"

  • framework and ecosystem
  • designed to be flexible and incrementally adoptable
  • can be used in
    • enhancing static HTML without a build step
    • embedding as Web Components on any page
    • Single-Page Application (SPA)
    • Fullstack / Server-Side Rendering (SSR)
    • Jamstack / Static Site Generation (SSG)
    • targeting desktop, mobile, WebGL, and even the terminal

Overview of Vue JS

  • Declarative rendering
  • Component composition

Declarative rendering

  • Declaring Reactive State
  • Declaring Methods - methods()
    • this is bind automatically (no arrows here!)
    • accessible in template (mostly as event listeners)
  • Deep Reactivity - by default
    • detects even mutation of nested obj or array
  • DOM Update Timing - not synchronous, buffered until the nextTick(), fixable with async..await
    • in the update cycle - ensures each component updates only once (with all the state changes)
  • Stateful Methods - dynamically created methods
    • in reused components - to avoid interference use created() lifecycle hook

Component composition

  • SFC - Single-File Components
  • Options API vs Compositions API - two styles

SFC

  • HTML-like file format (*.vue)
    • logic (JS), template (HTML), and styles (CSS) - together
    • for build-tool-enabled projects
      • recommended way
  • Example
<script>
export default {
  data() {
    return {
      coursesInCart: 0
    }
  }
}
</script>

<template>
  <button @click="coursesInCart + 1">You have: {{ coursesInCart }} courses in your bucket!</button>
</template>

<style scoped>
button {
  font-size: 48px;
}
</style>

Options vs Composition

API Styles in Vue
Compare of Options API Composition API
Component's logic Object with options (data, methods, mounted, etc) Imported API functions (ref, reactive, onMounted, etc)
Properties Exposed on this in functions Declared with functions (ref)
Syntax (some bits only) the usual <script> <script setup>, less boilerplate
Common web use cases covered covered
Centered on component instance (this), beginner-friendly, organized state directly in function, free-form, more flexible
For production use no build tools, low-complex cases builds and full apps (+SFC)

Options vs Composition Con't

Options vs Composition, Example

Options Composition 
<script>
export default {
  // Properties returned from data() become reactive state and will be exposed on `this`.
  data() {
    return {
      invoice: { id: 'INV_integer', type: 'default', owner: 'countryPrefix_franchisee' }
    
  },

  // Methods are functions that mutate state and trigger updates.
  // They can be bound as event handlers in templates.
  methods: {
    setInv() {
      this.invoice = { id: 'INV2378', type: 'consultancy', owner: 'NPUK_franchisee' }
    }
  },

  // Lifecycle hooks are called at different stages of a component's existence.
  // This function will be called when the component is mounted.
  mounted() {
    console.log(`The invoice for this ${this.invoice.type} is ${this.invoice.id}.`)
  }
}
</script>

<template>
  <button @click="setInv">Send invoice from: {{ invoice.owner }}</button>
</template>

<script setup>
import { ref, onMounted } from 'vue'

// reactive state
const invoice = ref( { id: '', type: '', owner: '' } )

// functions that mutate state and trigger updates
function setInv() {
  invoice.value = { id: 'INV2378', type: 'consultancy', owner: 'NPUK_franchisee' }
}

// lifecycle hooks
onMounted(() => {
  console.log(`The default invoice has an empty ID: ${invoice.value.id}.`)
})
</script>

<template>
  <button @click="setInv">Send invoice from: {{ invoice.owner }}</button>
</template>


Setting up a development environment

vue itself (later on)

npm create vue@latest
# answer the interactive questions accordingly (proj-name, ts, routing, pinia, testing, etc)
cd proj-name ; npm i ; npm run format ; npm run dev

OR 

npx create-vue proj-name
# answer the questions
cd proj-name ; npm i ; npm run format ; npm run dev

Creating your first application

Build game "Find the jewel".
The objective of the game is to find a random computer-chosen jewel in as few tries as possible.

Approach:
* First think about the functionality we want to offer
* Second think about the data and behavior that can support the functionality
* Third think about how to build a user interface for it

Test it with 'live-server' (if not yet installed in the training machine, run 'sudo npm i -g live-server')
* in command line go to application's root folder and execute the command 'live-server --cors'
  1. Designing the component
    • Detailing the features that we want the app to support
      • Choosing random jewel (origJewel)
      • Providing input for a user to find the jewel (findJewel)
      • Tracking the number of tries already made (howManyTries)
      • Giving the user hints to improve their try based on their input (hinting)
      • Giving a success message if the user found the proper jewel (hinting)
    • Determining what we need to display to the user and what data we need to track
      • Names in round brackets above are the properties that will support those features
      • We need to include these properties in our component

Exercise

Working with Templates

  • Vue uses an HTML-based template syntax
    • declaratively binds
      • the rendered DOM to the underlying component instance's data
  • syntactically valid HTML
    • parseable by spec-compliant browsers and HTML parsers
  • compiled into highly-optimized JS - when the app state changes
    • intelligently re-renders the minimal no of components
    • applies the minimal amount of DOM manipulations
  • can be written directly as render functions instead
    • JSX is optionally supported
    • but not the same level of compile-time optimizations

Methods and computed properties

Method - manages actions, mutates state, etc

  • New option - methods : { setInvoice(){} }
  • Or just functions in composition's setup() { function setInvoice(){} }
  • always called whenever a re-render happens
    • must be returned together with properties

Computed property - solves complex logic that includes reactive data

  • New option - computed: { getInvoicesPerFranchisee(){} }
  • Or just ref in composition's setup, wrapped into computed()
  • cached based on its reactive dependencies
  • getter-only by default, changeable with giving it the setter
  • should be side-effect free, don't:
    • mutate other state
    • make async requests
    • mutate the DOM inside a computed getter
    • also mutating its own computed value

Exercise

Reactive programming

  • unobtrusive reactivity system
  • adjust to changes in a declarative way
  • Proxies for reactive objects
  • getters/setters for refs (simple properties)
  • Reactive Effect => watch(option) or watchEffect()(api)
  • Runtime vs Compile-time - Vue works with Runtime
  • Debugging (only in dev mode!)
    • components - hooks again: renderTracked() and renderTriggered()
    • computed and watcher - onTrack() and onTriger() callbacks in computed() 2nd arg
  • Ext state systems - shallowRef

Directives and data rendering

Data binding - syntax Name:Argument.Modifiers="Value"

  • {{ }} - text interpolation, JS expressions (not statements!); interpreted as plain text
  • v-html - raw HTML somewhere
  • v-bind: / : - attribute directive / shortcut
    • from Vue 3.4+ even shorter, if same name :id="id" => :id
    • multiple attrs - just v-bind without argument

Built-in directives, some

Syntax - prefix v-

  • v-if, v-else - logic for adding/removing elements; destroying
    • v-show - conditional rendering; hiding only (display prop)
  • v-for: - listing elements; v-for="(el, index) in listOfEls" :key="index"
  • v-on: / @ - handling events; v-on:click="updateInv"
    • v-on:[eventName] - dynamic, 'eventName' should be string or null
    • v-on:submit.prevent - with modifier, does event.preventDefault()
  • v-bind:[attrName] - also dynamic, 'attrName' should be string or null
  • v-model - 2 way data binding, between model(data) and view(template)
  • more here https://vuejs.org/api/built-in-directives.html

Exercise

Dividing the application into smaller, self-contained components

  • Component Pattern instead of MVC
  • Constructs
    • expressions, data binding syntax
  • Change detection
  • Web components

Component pattern

In web applications

  • No messes of spaghetti code in applications
  • Reasoning about specific parts of the application in isolation from the other parts
  • Maintenance costs are less
    • Each component's internal logic can be managed separately
    • No affecting the other parts of the application
  • Self-describing components
    • Makes the application easier to understand at a higher level of abstraction

Constructs

  • Usually they live in the HTML template
  • They are linking the view HTML and component code
  • Similar to standard HTML with new symbols:
    : property bindings (v-bind)
@ event bindings (v-on)
{{ }} expressions (interpolation)

Props VS Emitting

Components can talk

  • one-way bound, parent to child - props
<!-- in parent, called 'current-invoice' -->
<voided-invoice v-bind:reasons="getReasons"/>
(...) methods: { getReasons(){} }

<!-- in child, called 'voided-invoice' -->
props: { reasons: { type: Object, required: true } },
template: `<div>{{ reasons.overdue }}</div>`
  • one-way bound, child to parent - emitting
<!-- in parent, called 'current-invoice' -->
<voided-invoice v-bind:reasons="getReasons" @void-confirmed="excludeInv"/>
(...) methods: { getReasons(){}, excludeInv(){} }

<!-- in child, called 'voided-invoice' -->
props: { reasons: { type: Object, required: true } },
template: `<div>{{ reasons.overdue }}</div>`
(...) methods: { giveConfirmation(){ this.$emit('void-confirmed', this.confirmed) } }


Change detection ⌘

  • State maintenance
  • Change detection
State maintenance ⌘
  • Vue apps are dynamic
  • Dynamic values are kept up-to-date as the data in an application gets updated
  • Component is the container for the state
    • all the properties in the component instance and their values are available for the template instance that is referenced in the component
    • we can use these values directly in expressions and bindings in the template without having to write any plumbing code to wire them up
Change detection ⌘

Vue keeps track of changes in the component as it runs

  • Is reacting to events in the application
  • Uses change detectors
    • Go through every component to determine whether anything has changed that affects the view
    • Event triggers the change detection cycle
      • Identifies that the property that is being used in the view has changed
    • Updates the element in the view that is bound to property with the new value of it
Change detection Con't ⌘
  • Multi-step process where Vue
    • First updates the components and domain objects in response to an event
    • Then runs change detection
    • Lastly re-renders elements in the view that have changed
  • This is done on every browser event
    • Also other asynchronous events (XHR requests, timers, etc)
  • one-way data binding
    • Change detection in Vue is reactive and one way
    • Makes just one pass through the change detection graph
    • It vastly improves the performance of Vue

Web components ⌘

Standards for web browsers

  • Custom elements
  • Shadow DOM
  • Templates

Custom elements ⌘

Enable new types of element to be created

  • Other than the standard HTML tag names (div, p, etc)
  • Custom tags provides a location on the screen that can be reserved for binding a component
  • Separation of component from the rest of the page
    • Makes it possible to become truly self-contained

Shadow DOM ⌘

Provides a hidden area on the page for scripts, CSS, and HTML

  • Markup and styles in it
    • Will not affect the rest of the page
    • Will not be affected by the markup and styles on other parts of the page
  • Component can use it to render its display

Templates ⌘

Repeatable chunks of HTML

  • Have tags that can be replaced with dynamic content at runtime using JavaScript
  • Web Components standardize templating
    • Provide direct support for it in the browser
  • Can be used to make the HTML and CSS inside the Shadow DOM used by the component dynamic

Exercise

Routing

Vue Router - separate library, officially-supported, recommended by Vue creators

  • official solution especially for Vue's single page apps (SPAs)
    • to tie the browser URL to the content seen by the user
      • <RouterView />
    • user navigates around the application
      • <RouterLink to="/courses">Training Catalog</RouterLink>
    • then the URL updates accordingly
      • $route.fullPath
    • and page doesn't need to be reloaded from the server
    • built on Vue's component system
    • configurable routes - component shown for each URL path
      • const routes = [ { path: '/courses', component: CoursesView }, { path: '/training-methods', component: TrainingMethodsView }, ]
    • declaring router and using it with app
      • const router = createRouter({ history: createMemoryHistory(), routes, })
      • createApp(App).use(router).mount('#app')
    • related docs - https://router.vuejs.org/
  • alternatives - other community libraries or our own vanilla plugin/component/composition

Exercise

Managing state (Pinia)

  • For simple and medium apps - Vue's own Reactivity API
    • Vue's reactivity system is decoupled from the component model (extremely flexible!)
    • first - try lifting the state up
    • if we go bigger, then use top level store.js
      • put data and shared methods there
      • use them in components, i.e. <button @click="store.getInvoiceDetails()">
  • large-scale production apps - use Pinia
    • state management library (previous was Vuex)
    • maintained by the Vue core team(!)

Managing state con't

Pinia implements considerable things

  • conventions for team collaboration are stronger
  • better integration with Vue DevTools
    • timeline, in-component inspection, time-travel debugging
  • Hot Module Replacement
  • Server-Side Rendering support

Exercise

Testing your application

Mostly

  • Unit - inputs produce the expected output or side effects (function, class, or composable)
  • Component - mounts, renders, can be interacted with, and behaves as expected.
    • import more code, more complex, executes longer
  • End-to-end - features that span multiple pages
    • real network requests to our production-built app
    • often involve backend (database, etc)
    • Vue guys recommend Cypress, other popular options: Playwright, Nightwatch, WebdriverIO
  • How? - use Vitest
    • designed, created and maintained by Vue / Vite team members
    • integrates with Vite-based projects with minimal effort, is really fast
    • More here https://vitest.dev/
  • Good alternatives - jest, jasmine

Deploying your application to production Vue-CLI

  • Vite as a replacement for Vue-CLI
    • npm run dev
    • npm run build
    • interactive CLI commands:
press r + enter to restart the server
press u + enter to show server url
press o + enter to open in browser
press c + enter to clear console
press q + enter to quit

Scaling your application

Helpers

Exercises

  1. Simple ftj - discussing app skeleton (index.html, main.js)
    1. Map the state in data() (main.js)
      • add all the properties from designing part
      • use this property below as our main model for now
      • jewels: ['ruby','diamond','agate','amber','aquamarine','amethyst','opal','tourmaline','emerald','onyx','pearl','sapphire']
    2. Update our main html template with howmManyTries
      • Exercise: improve it with dynamic data (index.html)
      • observe it in the browser - use Vue dev-tools
  2. Design the engine of our game - initGame() method
    • it should set values for our game properties
    • supposed to randomly choose the jewel ( Math.floor((Math.random() * 12) + 1) )
    • and of course allow to cheat (-'
    • oh, don't forget to spoil(run) it, do it with hook, yeahhh.. let's go meaty-nasty now! (--'
  3. Describe first jewel in a new paragraph - say "ruby is red"
    • use computed property
    • for that let's improve slightly our model:
      gems: [
  { id:1, jname: 'ruby', jcolor: 'red' },
  { id:2, jname: 'diamond', jcolor: '#b9f2ff' },
  { id:3, jname: 'agate', jcolor: 'blue' },
  { id:4, jname: 'amber', jcolor: 'orange' },
  { id:5, jname: 'aquamarine', jcolor: 'aquamarine' },
  { id:6, jname: 'amethyst', jcolor: 'violet' },
  { id:7, jname: 'opal', jcolor: 'turquoise' },
  { id:8, jname: 'tourmaline', jcolor: 'black' },
  { id:9, jname: 'emerald', jcolor: 'green' },
  { id:10, jname: 'onyx', jcolor: 'gray' },
  { id:11, jname: 'pearl', jcolor: '#EAE0C8' },
  { id:12, jname: 'sapphire', jcolor: '#2554C7' },                       
]
  4. Communicate The Gamers - win or loose, huh? (---'
    1. interactive message shown to gamer (Drax the Destroyer)
      • first use only one type of directive (&
        • Exercise: improve this section with game logic (index.html)
      • test it in Vue dev-tools
      • later on, improve it with two different directives (&
    2. do same thing, but play hide-and-seek only
      • test it in Vue dev-tools
  5. "Fire!! Gather them together, quickly!" - grouping kids (2Kill'em all..), (----'
    1. Show all the jewels in one view (use 'ul')
    2. For each jewel add its length at the end - ruby 4
      • ..then divide it by the size of jewels array.. - ruby 0.3333333333333333
      • ..and then round it to integer.. - ruby 1
      • ..and then wrap it with logic: if 1, show ' is long', otherwise show ' is short'.. - ruby is short
      • ..and then - improve it with (...) ?? (small discussion together)
  6. Help the gamer - when the number of tries is 5, Restart game button should become huge (48px)
    • add new css class(.gameKiller) and bind it (how?)
  7. "Bring me some action!" - Sly?
    1. Restarting the game should re-initialize our state in model
    2. Mower the title - when Bloody is hovered, change its background to red..
      • do it for only h2 elements - use this.$el.querySelector()
      • Exercise: improve this header with a red background, when hovered (index.html)
  8. "Take me to the battle!" - Arnie?
    • Let's finish our engine - Verify button plays the game
    • we need two-way bounds, use proper directive then
    • what about the engine(random choice) itself, huh? something there is just wrong.. what? how to fix it? (-'
  9. "What about sex, huh?" - Bridget?
    1. Make sure gamer can add new jewel
      • cloning is prohibited.. (no same jewel twice)
      • no ghosts too.. (empty jewel)
    2. HOMEWORK: separate one gem from the pack and.. kill it! (add Remove button)
  10. "True pack never leaves any fellow behind!" - Thor?
    1. List gems in divs
      • use gem id as key
      • make gems shine (colorize them accordingly)
    2. Improve gem description (p), it should use the actual hovered gem
      • new property (pointing the gem), new method (handling the choice)
  11. "How to kill one stone with many birds?" - my Boss? (--------------'
    1. Cut gems related family and put it into its own separate - guess what..? (-;
      • create new folder components and filo components/Gems.js - app.component('gems', {})
      • synchronize it with parent's main template (index.html)
      • add new html snippet as option - template: /*html*/ `<div>works</div>`
      • and finally parent calls the child - and.. it refuses and it cries and it.. (you know what, the usual..)
      • play it with dev-tools
      • move here everything related only to gems (not jewels! leave them be)
    2. "I'm a sex machine!" - adding new gem in another component (-'
      • gems should be the father.. yup.. 3rd level now(!), yay !!
      • use full form element
      • use input as button
    3. "Make them talk!" - Don Padre(The Godfather)?
      • root component tells gems what should be in its brand new h4 list remark (props)
        • mount another instance of gems, do not pass the prop - what can you tell? (-'
      • gems tells son how many brothers and sisters he has (props)
      • add-gem tells father what to do and how.. (ahhh.. kids.. they become grown-ups so fast these days..)
        • use emitting and custom event
  12. Migration - painful, boring(!?), nightmare..
    • Migrate our app into Composition style
    • use official vue CLI
    • use TS (TypeShit.. oups.. TypeShut.. aaahh.. TypeScript)
    • why tooling and bundling and change-detection and hot-reloading and..
  13. Routing - how to navigate with a yellow submarine
    • route our ftj app
  14. State management - SCRUMs, UMLs, NVCs, etc
    • Pinia and its flavors
  15. "Stack it in your..!" - Hamish (the "detective")?
    • Wrapping into full-stack, with db, rest api, etc
  16. ? (HOMEWORKS)


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