250

May 20th, 2020 × #svelte#webdev#javascript

Scott Teaches Wes Svelte and Sapper

In this episode Scott teaches Wes about Svelte, a new JavaScript framework that compiles away unused code for blazing fast performance. They cover features like built-in reactivity, cleaner templates vs JSX, routing with HTML anchors, and animations/transitions.

Wes Bos

Wes Bos Host

Scott Tolinski

Scott Tolinski Host

or
Show Notes Transcript

In this episode of Syntax, Scott teaches Wes about Svelte and Sapper — general premise, best practices, and more!

Sanity - Sponsor

Sanity.io is a real-time headless CMS with a fully customizable Content Studio built in React. Get a Sanity powered site up and running in minutes at sanity.io/create. Get an awesome supercharged free developer plan on sanity.io/syntax.

Stackbit - Sponsor

Stackbit offers developers tools that enable things like inline content editing, live previewing of content changes, and collaboration features on your Jamstack site, without code changes. That's why Stackbit is the best way to Jamstack. stackbit.com

Show Notes

03:14 - General premise

  • Sapper compiles away, removing framework code from build
  • Component & Props based
  • Easy reactivity
  • Built-in tools like animation
  • Template-based

07:57 - Svelte 101

  • .svelte files
  • Files can include <script>, <style>, and straight-up CSS
  • Variables are used in templates via {var} - <img {src} /> even works
  • Import component and use just like React and Vue

10:49 - Stylin'

  • All styles are scoped by default
  • global() to wrap around global declarations
  • Language type sass to use sass

12:22 - Reactivity

  • Baked in
    • let count = 0
    • count = count + 1 will reactively update in template
    • variables are essentially state
    • $: double = count + 2 - to create a reactive variable that updates when another variable updates
    • $: console.log(count) = will run whenever count is update a-la useEffect
    • $: if (count >10) = same... reactive if
    • <input bind:value={name} > updates let name in script

15:55 - Props

  • Same was React, but need to be exported before they can be used
  • Seems counterintuitive, but you get over it quickly
  • EZ defaults export let answer = 'a mystery';
<script>
import Nested from './Nested.svelte';
</script>

<Nested answer={42}/>

<script>
	export let answer = 'a mystery';
</script>

<p>The answer is {answer}</p>

20:08 - Template logic

  • If statements {#if user._id} {/if}

  • Loops {#each cats as kittens}

  • Promise tags

{#await promise}
	<p>...waiting</p>
{:then number}
	<p>The number is {number}</p>
{:catch error}
	<p style="color: red">{error.message}</p>
{/await}

23:12 - Events

  • <button on:click={func} />
  • On directive
  • Functions can also be inline
  • Modifiers
<button on:click|preventDefault={handleClick}>
	Click me
</button>

26:11 - Baked-in goodies

  • Animation
  • Dimensions
<div bind:clientWidth={w} bind:clientHeight={h}><span style="font-size: {size}px">{text}</span></div>
  • Lifecycle methods
  • Advanced State Via Stores
    • A store is simply an object with a subscribe method that allows interested parties to be notified whenever the store value changes.
  • import { writable } from 'svelte/store';
  • export const count = writable(0);
  • count.update(0)
  • Slots
  • React helmet like stuff, ie svelte:head

36:39 - Sapper

  • Similar to Next.js
  • Folder routes
  • Static export with all of the good stuff like service workers and preloading

××× SIIIIICK ××× PIIIICKS ×××

Shameless Plugs

Tweet us your tasty treats!

Share