Michael North "The Road to Native Web Components"

Mike North
CTO Levanto Financial
The Road to Native Web Components

INTRODUCTION
WHO’S THIS GUY?
▸ CTO Levanto Financial
▸ frontendmasters.com instructor
▸ Product Guy
▸ I do a lot of JavaScript OSS stuff
▸ I work with Ember & React a lot

INTRO
DO YOU USE WEB COMPONENTS? (YES)

INTRO
THE W3C WEB COMPONENT SPEC
HTML IMPORTS
HTML TEMPLATES
CUSTOM ELEMENTS
SHADOW DOM

INTRO
HTML IMPORTS
▸ require() for HTML
▸ onload, onerror events
▸ can bring in css/html/js
▸ closure-like js characteristics

INTRO
CUSTOM ELEMENTS
▸ Custom HTML vocab
▸ Life-cycle
▸ Extensibility
▸ Interoperability (we hope?)

INTRO
HTML TEMPLATES
▸ Inert HTML in the DOM
▸ Defer loading / rendering
▸ Think: handlebars/jade/etc…

INTRO
SHADOW DOM
▸ CSS Encapsulation
▸ DOM encapsulation
▸ Each component has own
subtree w/in parent page

<!DOCTYPE html>
<html>
<head></head>
<body>
<template id="something">
<div class="frame">
<h3 class="title">I am a title</h3>
<p class="body">I am the body</p>
</div>
</template>
</body>
</html>

<style type="text/css">
.title {
font-size: 24px;
}
</style>

<script type="text/javascript">
</script>

<div class="frame">
</div>
</template>

// Grab the template
var tmpl = document.querySelector(‘#something');
Add the cloned document fragment to the DOM
document.body.appendChild(
// Clone the template's document fragment
document.importNode(tmpl.content, true)
);

http://codepen.io/TrueNorth/pen/xbyVgL?editors=101

HOW DO FRAMEWORKS
HANDLE THIS?

define('examples/templates/index', ['exports'], function (exports) {
'use strict';
exports['default'] = Ember.HTMLBars.template((function() {
return {
...
buildFragment: function buildFragment(dom) {
var el0 = dom.createDocumentFragment();
var el1 = dom.createTextNode("Hello, ");
dom.appendChild(el0, el1);
var el1 = dom.createElement("strong");
var el2 = dom.createComment("");
var el2 = dom.createTextNode(" ");
var el2 = dom.createComment("");
var el1 = dom.createTextNode("!");
return el0;
},
buildRenderNodes: function buildRenderNodes(dom, fragment,
contextualElement) {
var element0 = dom.childAt(fragment, [1]);
var morphs = new Array(2);
morphs[0] = dom.createMorphAt(element0,0,0);
morphs[1] = dom.createMorphAt(element0,2,2);
return morphs;
},
statements: [
["content","firstName",["loc",[null,[1,15],[1,28]]]],
["content","lastName",["loc",[null,[1,29],[1,41]]]]
],
...
};
}()));
});

LAZY LOADING
Lazy engines, JIT template compiler
Webpack chunking
Webpack chunking

APPLICATION DOM
COMPONENT
SHADOW DOM

SHADOW DOM
ENCAPSULATION http://codepen.io/mike-north/pen/OPBNmq?editors=101

SHADOW DOM
CSS ENCAPSULATION
▸ CSS rules do not usually pierce
shadow roots
▸ CSS deﬁned inside the shadow
root only affects that DOM
▸ :host pseudo-selector for
component boundary
▸ ::shadow penetrates shadow
roots
▸ /deep/ is deprecated
// Inside shadow root
:host {
border: 1px solid red;
}
:host(.hover) {
border: 1px solid blue;
}
// Outside shadow root
#my-thing::shadow p {
color: green;
}

CSS ENCAPSULATION
ember-css-modules
ember-component-css
“component styles”
react-css-modules

<textarea name="comment" id="" cols="30" >
This is the content of my textarea
</textarea>
SHADOW DOM
CONTENT PROJECTION

http://codepen.io/mike-north/pen/emPZMv?editors=1000

CONTENT PROJECTION
{{yield}}
2.x <ng-content>, 1.x ng-transclude
this.props.children

// Get document fragment of an import
var content = document
.querySelector('link[rel="import"]')
.import;

// Get document fragment of an import
var content = document
.querySelector('link[rel="import"]')
.import;
// From a <script> included with the import,
// access imported DOM
var $abc = document
.currentScript
.ownerDocument
.querySelector('.abc');

IMPORTING COMPONENTS
import MyComponent from 'my-component';

CUSTOM ELEMENTS
WHY IS THIS IMPORTANT
▸ Composable building
blocks
▸ Life-cycle
▸ Extensibility
▸ Alignment of HTML with
mental model of your UI

CUSTOM ELEMENTS
REGISTERING
// Extend a DOM element prototype
var MegaButtonProto =
Object.create(HTMLButtonElement.prototype);

CUSTOM ELEMENTS
REGISTERING
// Extend a DOM element prototype
var MegaButtonProto =
Object.create(HTMLButtonElement.prototype);
// Register your new element type
var MegaButton =
document.registerElement("mega-button", {
prototype: MegaButtonProto,
extends: "button"
});

CUSTOM ELEMENTS
ADDING A TEMPLATE
// Template
var infoBoxTemplate = document.querySelector('#info-pane-template');
// Extend a DOM element
var InfoBoxProto = Object.create(HTMLElement.prototype, {
createdCallback: {
value: function() {
// Create the shadow root
this.createShadowRoot().appendChild(
// Add the template to the shadow root
document.importNode(infoBoxTemplate.content, true)
);
}
}
});

// Template
var infoBoxTemplate = document.querySelector('#info-pane-template');
// Extend a DOM element
var InfoBoxProto = Object.create(HTMLElement.prototype, {
createdCallback: {
value: function() {
// Create the shadow root
this.createShadowRoot().appendChild(
// Add the template to the shadow root
document.importNode(infoBoxTemplate.content, true)
);
}
}
});
CUSTOM ELEMENTS
ADDING A TEMPLATE

CUSTOM ELEMENTS
Ember.Component
@Component
React.Component

DEMO
•Starting Point: http://codepen.io/TrueNorth/pen/PwdLrj
•Componentized: http://codepen.io/TrueNorth/pen/xbyqME
•HTML Importiﬁed: http://codepen.io/TrueNorth/pen/ogawLm

THANKS!
michael.l.north@gmail.com @MICHAELLNORTH

Michael North "The Road to Native Web Components"

More Related Content

What's hot (20)

Viewers also liked (20)

Similar to Michael North "The Road to Native Web Components" (20)

More from Fwdays (20)

Recently uploaded (20)

Michael North "The Road to Native Web Components"