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When in doubt,
trust the browser
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I'm Pieter Beulque
Front-end Developer
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Show what's possible
without the trusted
npm install
Goal of today
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Let's build a tweet embed
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Let's start!
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Custom Elements
Defining a re-usable component
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Custom Elements
Create your own
Progressive enhancement dream
Initializes whenever a node is added to the DOM
Anything is possible!
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Custom Elements
There's a very good introduction on
Google Developers' Web Fundamentals
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Shadow DOM
King of the castle
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Shadow DOM
Isolate component's DOM
Scope component styles
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Shadow DOM
Isolate component's DOM
Scope component styles
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Also
Also
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Shadow DOM
:host
& ::slotted()
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Shadow DOM
:host
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Shadow DOM
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Shadow DOM
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Shadow DOM
There's another very good introduction on
Google Developers' Web Fundamentals
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Browser support
Both can be polyfilled: github.com/webcomponents/polyfills
All evergreen browsers
Edge starting January 2020
No Internet Explorer
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Use it in production?
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Custom Elements
Yes, but…
Have been using it for 3 years
Has its limitations
Wouldn't use it for applications
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Shadow DOM
You could, but…
Falls short compared to frameworks
Feels clunky
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My thoughts
Great to sprinkle Javascript on top of content websites
More accessible out of the box than a everything-in-JS approach
Probably run into limits when using for applications
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North star
Custom Elements as a compile target
✨
Stencil & Svelte already support this.
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Let's move on
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Internationalization API
Intl.RelativeTimeFormat
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Internationalization API
Format dates, numbers and plurals
The browser already has all languages
Your browser knows your user's preferences
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Internationalization API
new Intl.RelativeTimeFormat(
'en',
).format(
value,
unit
)
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Internationalization API
new Intl.RelativeTimeFormat(
'en', // Any valid locale
).format(
value, // A number, positive = future, negative = past
unit // 'months', 'days', 'years', …
)
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Internationalization API
new Intl.RelativeTimeFormat('en').format(1, 'day')
in 1 day
new Intl.RelativeTimeFormat('nl').format(-1, 'year')
1 jaar geleden
new Intl.RelativeTimeFormat('fr').format(0, 'month')
dans 0 mois
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That's not very human
new Intl.RelativeTimeFormat('en').format(1, 'day')
in 1 day
new Intl.RelativeTimeFormat('fr').format(0, 'month')
dans 0 mois
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That's not very human
new Intl.RelativeTimeFormat(
'en', { numeric: 'auto' }
).format(1, 'day')
tomorrow
ce mois-ci
new Intl.RelativeTimeFormat(
'fr', { numeric: 'auto' }
).format(0, 'month')
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Browser support
There's a polyfill from Polyfill.io: github.com/andyearnshaw/Intl.js/
Chrome, Firefox and Opera
No Safari
No Edge or Internet Explorer
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Use it in production?
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Internalization API
Definitely!
Save bandwidth on translation files
All edge cases handled automatically
Locale 'default' uses your user's preferences
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1 + 1 = 2
Let's recap
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Let's build a reusable, standalone component
that turns a time into a human-readable, relative time
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Define attributes to
watch for changes
Run the formatter
on every change
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Define attributes to
watch for changes
Run the formatter
on every change
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Zero dependencies.
Self-contained. Re-usable.
20 LOC.
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OK, I cheated a little.
The code that calculates the date difference
adds another 30 lines.
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All in a single file?
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ES Modules
Do you really need a bundler?
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The browser knows what to do.
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Browser support
Everywhere but IE & UC Browser
Serve bundle as a fallback, thanks to nomodule
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Progressive Enhancement is beautiful
And browsers are amazingly good at it.
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Use it in production?
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ES Modules
Yes, with caution
Definitely needs HTTP/2
No problem for small amount of modules
Watch out for huge dependency trees
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North star
ES Modules as a bundling target
✨
Rollup & Parcel already support this.
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One more thing
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Built-in lazy loading
Unofficial, Chrome-only
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So remember…
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When in doubt,
trust the browser
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Thank you!
Questions?
@pieterbeulque