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Introducing
Web Components
#FELOneDay 09/13
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Peter Gasston
@stopsatgreen
broken-links.com
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Creative Technologist
/ Front-end lead
rehabstudio.com
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1. Subject to change
2. There will be code
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Web Components
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The secret of
Ultimate Power!
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{demo}
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What The
FrontEndLondon?
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No content
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Shadow DOM
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Rendered but
invisible in
the DOM.
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No content
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Make your own
Shadow DOM
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Shadow Root
DOM
Host
Cat
Wars
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Shadow root
var newRoot = $(foo).createShadowRoot(),
newEl = '
Shadow world!
'; newRoot.innerHTML = newEl;Slide 16
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Hello world!
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Hello world!
Shadow world!
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{demo}
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Shadow DOM
Real
DOM
Shadow
DOM
Shadow
Host
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A DOM hidden
inside the DOM.
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Ultimate Power!
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A problem
Shadow
DOM
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No content
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.foo {
color: #00f;
}
The problem
…
div.foo {
color: #f00;
}
…
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The Solution
Encapsulation
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Encapsulation
1. It has all it needs.
2. Nothing gets in,
nothing gets out.
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Encapsulation
1. We run things,
things don’t run we.
2. Don’t take nothing
from nobody.
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●
Extra network requests
●
Multiple rendering contexts
●
CORS conflicts
●
Generally a bit shit
Encapsulation
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Web Components
Better encapsulation
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a set of emerging
standards aimed at
making reusable
widgets.
Web Components:
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the biggest change
to web dev since
XMLHttpRequest.
Web Components:
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Shadow DOM
Templates
Custom elements
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Shadow DOM
Templates
Custom elements
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Shadow DOM
Templates
Custom elements
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Mustache, etc.
<h2>Hello world!</h2>
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The template element
Hello world!
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The markup
is inert.
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The template element
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The template element
Hello world!
ContentSlide 40
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The content object
var clone = $(foo).content.cloneNode(true),
bar = document.getElementById('bar');
bar.appendChild(clone);
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Templates
#FELOneDay
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Templates
#FELOneDay
Hello world!
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The markup
is active.
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Templates + Shadow DOM
var newRoot = $(foo).createShadowRoot(),
clone = $(bar).content.cloneNode(true),
newRoot.innerHTML = clone;
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The content element
Hello world!
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Good afternoon, London!
The content elementHello world!
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Templates + Shadow DOM
var newRoot = $(foo).createShadowRoot(),
el = document.createElement('content');
newRoot.innerHTML = el;
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Templates
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HTML Imports
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HTML Imports
var lnk = 'link[rel="import"]',
impt = document.querySelector(lnk),
tpl = lnk.import.getElementById('foo'),
clone = tpl.content.cloneNode(true);
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HTML Imports
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Shadow DOM
Templates
Custom elements
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Custom elements
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Custom elements
document.register('front-end');
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Custom elements
+ shadow DOM
+ templates
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Custom elements
document.register('front-end', {
extends: 'button'
});
Go
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Custom element API
var fe = Object.create(
HTMLElement.prototype
);
fe.foo = function() { // Something };
document.register('front-end', {
prototype: fe
});
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The element element
…
#document-fragment
…
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Fully
encapsulated
& reusable
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Encapsulation
Reusability
Portability
Shadow DOM
Templates
Custom elements
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That’s basically it.
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No content
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Appendix A:
More about
Encapsulation
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The shadow boundary
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The shadow boundary
CSS
& JS
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The shadow boundary
CSS
& JS
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Shadow root
var shad = newRoot.shadowRoot;
shad.querySelector('h2');
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The shadow boundary
CSS
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.applyAuthorStyles
newRoot = foo.createShadowRoot();
newRoot.applyAuthorStyles = true;
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The shadow boundary
CSS
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Pseudo-elements
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Pseudo-elements
::-webkit-progress-bar
::-webkit-progress-value
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{demo}
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The part attribute
var newRoot = el.createShadowRoot(),
newEl = '
…
'; newRoot.appendChild(newEl);Slide 75
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Show me your parts
#document-fragment
.foo::part(apes) { color: red; }
Shadow world!
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Appendix B:
Scope
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Hello
p { color: #f00; }
World!
Again
Scoped stylesSlide 78
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Hello
p { color: #f00; }
World!
Again
Scoped stylesSlide 79
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css = 'p { color: #f00; }';
newRoot.appendChild(css);
Shadow scope
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Custom properties
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(don’t call them
variables)
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body {
var-highlight: #f00;
}
Custom properties
h1 { color: var(highlight); }
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Custom properties
.foo {
var-highlight: #00f;
}
body {
var-highlight: #f00;
}
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Custom properties
#document-fragment
h1 { color: var(highlight); }
body {
var-highlight: #f00;
}
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Almost done
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Shadow DOM
Shadow DOM API
Templates
HTML imports
Custom elements
Scoped styles
Custom properties
Browser support
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87
Polymer project
Polymer project
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Useful links
polymer-project.org
updates.html5rocks.com/tag/webcomponents
plus.google.com/+EricBidelman
mozilla.github.io/brick
customelements.io
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Peter Gasston
@stopsatgreen
broken-links.com