Vue.js London Conference

Alex Puia

Thomas Truong

Agenda

  • Animations in Vue
  • Scripting in Style
  • Performance
  • Composition API
  • Lightning talks
  • Resources
  • Questions

Animations in Vue

Adam Jahr

Why animate?

  • Directing focus
    • Guide users how to use your app
    • Grab focus of our user's attention
  • Inspiring action
    • Remove distraction
    • Primal human instinct

Transitions

  • Vue's transition component
  • Entering Transition vs Leaving Transition
  • Page Transition
  • Group Transition

Transition Component

Vue's Transition Component

Scripting in Style

Maya Shavin

The FEAR of CSS

Scaling

  • Global namespace
  • Implicit dependencies
  • Code Maintenance/DEAD code
  • Minification
  • Sharing Constants
  • Non-deterministic order of source

Not the Bruce we deserved,

but the Bruce we need

/* darknight.css */

.bruce {
  color: 'black';
}
/* smash.css */

.bruce {
  color: 'green';
}
/* yippeekiyay.css */

.bruce {
  color: 'red';
}
<div class="bruce">
 I am Bruce
</div>

Bruce

Bruce

Bruce

!important 🤮

React Inline Style

const pStyle = {
  fontSize: '15px',
  textAlign: 'center'
};

const Box = () => (
 <p style={pStyle}>Get started with inline style</p>
);
  • Readability
  • Scalability
  • Animations
  • Media Queries

CSS Modules

.title {
  background-color: red;
}
  • NOT full extendable CSS in global scope
  • NAMING can still have collisions
  • NO easy way for theming
  • NOT really CSS-in-JS as it's in a separate file
import style from "./styles.css"

element.innerHTML = `<div class="${styles.title}"> Examples </div>`;
<div class="_styles__title_2805"> Example </div>

Styled Components

const Button = styled.button`
  background: ${props => props.primary ? "white", 'black'};
`;

render(<div>
  <Button primary>Primary</Buttons>
  <Button>Normal</Button>
</div>)
  • Creates a new class for every dynamic prop variable
  • Browser still needs to:
    • Download
    • Load
    • Read
    • Parse the CSS
  •  
    • Inject into stylesheet
    • HTML can paint
    • No cache

Conclusion

  • Use the right tool for the right job
  • CSS Modules
    • ​Component
  • CSS/SCSS
    • Global

IDENTIFYING AND SOLVING PERFORMANCE ISSUES IN VUE APPLICATIONS

Filip Rakowsky

What influences loading time performance

Sample Vue app modules

Sample Vue app modules

Solutions

  • Code Splitting
  • Lazy Loading
  • Dynamic Import

Rule #1 - Split your code per route

Rule #2 - Load off-screen components lazily

Rule #3 - Load non-critical libraries lazily

Rule #4 - Choose your libraries carefully and try to find smaller equivalents if possible

https://bundlephobia.com/

Rule #5 - Prefetch lazily loaded resources

More performance wins

  • Lazy load images
  • Use functional components for lists
  • Optimise initial state when using ServerSide Rendering
  • Cache static assets in a Service Worker

Composition API

Greg Pollack

Thorsten LĂĽnborg

Jason Yu

Limitions of Vue 2

  • Readability as components grow
  • Code reuse patterns have drawbacks
  • Limited TypeScript Support

Readability

  • Logical concerns/features are organised by component options:​
    • ​Components
    • Props
    • Data
    • Methods
    • Computed Properties
    • Lifecycle Methods

Readability

Setup

  • Executes before:
    • ​Components
    • Props
    • Data
    • Methods
    • Computed Properties
    • Lifecycle Methods
  • Doesn't have access to this

Composition Functions

Mixins

  • Organise by feature
  • Conflict prone
  • Unclear relationships
  • Not easily reusable

Mixin Factories

  • Easily Reusable
  • Clearer Relationships
  • Weak Namespacing
  • Implicit property additions
  • No instant access at runtime

Scoped Slots

Composition Functions Vue 3.0

Lightning Talks

How to get your product owners to write your functional tests

Focus Management

Tab Index

 <h1 id="pageTitle" tabindex="-1">Tasks</h1>

Focus Directive

export default {
 ...,
 directives: {
    focus: {
      inserted: function(el) {
      	el.focus();
      }
    }
  }
};
  • A directive definition object can provide hook functions:
    • bind
    • inserted
    • update
    • componentUpdated
    • unbind
<h2 id="newTask" tabindex="-1" v-focus>
  Create New Task
</h2>

Awesome JS is Awesome

Renderless Event Component

Event Listening

<event-listener event="keyup" @fired="toggleVideo"/>
export default {
  components: {
    EventListener
  },
  methods: {
    toggleVideo (e) {
      if (e.code === 'Space') {
        const video = this.$refs.video
        video.paused ? video.play() : video.pause()
      }
    }
  }
}

$listeners

<event-listener @keydown.space="toggleVideo"/>
export default {
  components: {
    EventListener
  },
  methods: {
    toggleVideo (e) {
      const video = this.$refs.video
      video.paused ? video.play() : video.pause()
    }
  }
}

Resources

Other talks

"A new router to guide your apps"

Eduardo San Martin Morote

"D3 with Vue.js"

Ramona Biscoveanu

Slides + code

Slides + code

  • "Vue 3's Composition API" - Greg Pollock
  • "New Composition API" - Thorsten LĂĽnborg
  • "Live Coding using Composition Api" - Jason Yu
    • Keyboard Keyboard - Video

Slides + code

  • "Functional Programming" - Callum Silcock
  • "Focus Management" - Maria Lamardo
  • "Awesome JS is Awesome" - Guillaume Chao
  • "Application Shortcuts with a Renderless Event Component" - Rolf Haug
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