Ensuring Design Standards with
Web Components
University of Illinois WebCon – April 5, 2018
John Riviello
@JohnRiv
Chris Lorenzo
@Chiefcll

© Comcast

© Comcast

© Comcast

© Comcast

© Comcast

© Comcast

"Notebook beside the iPhone on Table" by PicJumbo is licensed under CC0 1.0

WHY?!?
1. Communication
2. Deviations
"Alone" by Pixabay is licensed under CC0 1.0

“Designers should build
products that solve needs
instead of spending time on
reinventions”
- Jack Zankowski
Creative Director, Comcast XD

"Mask, Ancient Artifact" by Pedro_Teixeira is licensed under CC0 1.0

"Abstract Business Code" by Pixabay is licensed under CC0 1.0

“And You Thought
Buttons Were Easy?”
- Nathan Curtis
Source: https://medium.com/eightshapes-llc/and-you-thought-buttons-were-easy-26eb5b5c1871

Source: https://medium.com/eightshapes-llc/and-you-thought-buttons-were-easy-26eb5b5c1871
$100/hour x 200 hours =
$20,000

Source: https://medium.com/eightshapes-llc/and-you-thought-buttons-were-easy-26eb5b5c1871
$20,000 x 50 teams =
$1,000,000

Source: https://medium.com/eightshapes-llc/and-you-thought-buttons-were-easy-26eb5b5c1871
$20,000 x 50 teams =
$1,000,000

"Books on Shelf in Library" by Pixabay is licensed under CC0 1.0

118 contributors
245 contributors
707 contributors

“A design system’s value is
realized when products ship
features using parts from
the system.”
- Nathan Curtis
Source: https://medium.com/eightshapes-llc/a-design-system-isn-t-a-project-it-s-a-product-serving-products-74dcfffef935

Design
System
Design &
Development
Source: http://atomicdesign.bradfrost.com/chapter-5/
Website
Pattern
Library
Make changes to a pattern
Applications and pattern library
both update to reflect changes

Google Polymer Project

#UseThePlatform
- Polymer Motto

Existing Frameworks
Applications
Web Platform
Web Components built with Polymer (or not)

What Are
Web Components?

What Are Web Components?
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll36
4 Specs

What Are Web Components?
37
Custom Elements
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
38
Custom Elements
•Provides a way for authors to build their own
fully-featured DOM elements.
<paper-tabs selected="0" scrollable>
<paper-tab>The first tab</paper-tab>
<paper-tab>Tab two</paper-tab>
<paper-tab>The third tab</paper-tab>
<paper-tab>Fourth tab</paper-tab>
</paper-tabs>
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
39 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
40
HTML Imports
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
41
HTML Imports
• Means to import custom elements
- <link rel="import" href="paper-tabs.html">
• Built-in deduplication
• Componetize the HTML, CSS & JavaScript
• Will be replaced by ES6 Modules
- import "paper-tabs.js"
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
42
HTML Imports
• Means to import custom elements
- <link rel="import" href="paper-tabs.html">
• Built-in deduplication
• Componetize the HTML, CSS & JavaScript
• Will be replaced by ES6 Modules
- import "paper-tabs.js"
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
43 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
44
Templates
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
45
• Used to declare fragments of HTML
- <template id="tab">
<div class="tab-content"></div>
</template>
• The element itself renders nothing
• Can be cloned and inserted in the document via
JavaScript, which will render the content
Templates
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
46 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
47
Shadow DOM
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
48
•Allows you to take a DOM subtree and
hide it from the document scope
•Hides CSS styles as well
•Common examples from HTML5 include:
<select>, <video>, & <input type="date">
Shadow DOM
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

What Are Web Components?
49 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

Source: https://www.webcomponents.org/element/PolymerElements/paper-tabs

Source: https://ebidel.github.io/material-playground/

How do I build my
Design System
using Polymer?

“A style guide is an artifact of design
process. A design system is a living,
funded product with a roadmap &
backlog, serving an ecosystem.”
- Nathan Curtis
Source: https://twitter.com/nathanacurtis/status/656829204235972608

You Need a TeamYou Need a Team

“Establish a high-quality,
brand-aligned experience across
our product through human
guidance and internal tools.”
- Jina Anne
Source: https://medium.com/salesforce-ux/the-salesforce-team-model-for-scaling-a-design-system-d89c2a2d404b
Salesforce.com Design Systems Team Objective:

"Person Workshop" is licensed under CC0 1.0 / Adjusted from original

Building Your Design System with Polymer
CSS
IS
AWESOME
60
Source: https://philipwalton.github.io/talks/2015-10-26/#7
• Managing global names
• Scoping/isolating styles
• Specificity conflicts
• Unpredictable matching
• Managing style
dependencies
• Removing unused code
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-element">
<template>
<style>
/* My Element Styles */
</style>
<p>Shadow DOM is awesome</p>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>

my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-element">
<template>
<style>
/* My Element Styles */
</style>
<p>Shadow DOM is awesome</p>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
Import Polymer.Element

my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-element">
<template>
<style>
/* My Element Styles */
</style>
<p>Shadow DOM is awesome</p>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
Styles we’ll be modifying

my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-element">
<template>
<style>
/* My Element Styles */
</style>
<p>Shadow DOM is awesome</p>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
Template contains <p>

my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-element">
<template>
<style>
/* My Element Styles */
</style>
<p>Shadow DOM is awesome</p>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
Polymer Boilerplate

my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-element">
<template>
<style>
/* My Element Styles */
</style>
<p>Shadow DOM is awesome</p>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
index.html:
<!doctype html>
<html>
<head>
<title>Shadow DOM Demo</title>
<script
src="bower_components/webcomponentsjs/webcomponent
s-loader.js"></script>
<link rel="import" href="my-element.html">
<style>
/* Main Document Styles */
</style>
</head>
<body>
<my-element></my-element>
<p>Paragraph in the main document</p>
</body>
</html>

my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-element">
<template>
<style>
/* My Element Styles */
</style>
<p>Shadow DOM is awesome</p>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
index.html:
<!doctype html>
<html>
<head>
<title>Shadow DOM Demo</title>
<script
src="bower_components/webcomponentsjs/webcomponent
s-loader.js"></script>
<link rel="import" href="my-element.html">
<style>
/* Main Document Styles */
</style>
</head>
<body>
<my-element></my-element>
<p>Paragraph in the main document</p>
</body>
</html>
Load Polyfills (if needed)

my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-element">
<template>
<style>
/* My Element Styles */
</style>
<p>Shadow DOM is awesome/p>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
index.html:
<!doctype html>
<html>
<head>
<title>Shadow DOM Demo</title>
<script
src="bower_components/webcomponentsjs/webcomponent
s-loader.js"></script>
<link rel="import" href="my-element.html">
<style>
/* Main Document Styles */
</style>
</head>
<body>
<my-element></my-element>
<p>Paragraph in the main document</p>
</body>
</html>
Import my-element.html

my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-element">
<template>
<style>
/* My Element Styles */
</style>
<p>Shadow DOM is awesome</p>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
index.html:
<!doctype html>
<html>
<head>
<title>Shadow DOM Demo</title>
<script
src="bower_components/webcomponentsjs/webcomponent
s-loader.js"></script>
<link rel="import" href="my-element.html">
<style>
/* Main Document Styles */
</style>
</head>
<body>
<my-element></my-element>
<p>Paragraph in the main document</p>
</body>
</html>
Styles we’ll be modifying

index.html:
<!doctype html>
<html>
<head>
<title>Shadow DOM Demo</title>
<script
src="bower_components/webcomponentsjs/webcomponent
s-loader.js"></script>
<link rel="import" href="my-element.html">
<style>
/* Main Document Styles */
</style>
</head>
<body>
<my-element></my-element>
<p>Paragraph in the main document</p>
</body>
</html>
my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-element">
<template>
<style>
/* My Element Styles */
</style>
<p>Shadow DOM is awesome</p>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
Body contains <my-element> & <p>

my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-element">
<template>
<style>
/* My Element Styles */
</style>
<p>Shadow DOM is awesome</p>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
index.html:
<!doctype html>
<html>
<head>
<title>Shadow DOM Demo</title>
<script
src="bower_components/webcomponentsjs/webcomponent
s-loader.js"></script>
<link rel="import" href="my-element.html">
<style>
/* Main Document Styles */
</style>
</head>
<body>
<my-element></my-element>
<p>Paragraph in the main document</p>
</body>
</html>
Flattened DOM Tree:
<body>
<my-element>
#shadow-root (open)
<style>...</style>
<p>Shadow DOM is awesome</p>
</my-element>
<p>Paragraph in the main document</p>
</body>

my-element.html:
<style>
p {
border: 3px solid #f60;
}
</style>

my-element.html:
<style>
p {
border: 3px solid #f60;
}
</style>
index.html:
<style>
p {
background-color: #9cf;
}
</style>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
p {
border: 3px solid #f60;
}
</style>
index.html:
<style>
p {
background-color: #9cf;
}
</style>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
}
p {
border: 3px solid #f60;
}
</style>
:host selector

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
}
p {
border: 3px solid #f60;
}
</style>
Flattened DOM Tree:
<body>
<my-element>
#shadow-root (open)
<style>...</style>
<p>Shadow DOM is awesome</p>
</my-element>
<p>Paragraph in the main document</p>
</body>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
}
p {
border: 3px solid #f60;
}
</style>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
}
p {
border: 3px solid #f60;
}
</style>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
}
</style>
See https://developers.google.com/web/updates/2016/06/css-containment for more information on contain

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
</style>
See https://developers.google.com/web/updates/2016/06/css-containment for more information on contain

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
:host([disabled]) {
outline-color: #ccc;
}
:host([disabled]) > p {
border-color: #ccc;
} ...
</style>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
:host([disabled]) {
outline-color: #ccc;
}
:host([disabled]) > p {
border-color: #ccc;
} ...
</style>
index.html:
<my-element></my-element>
<p>Paragraph in the main
document</p>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
:host([disabled]) {
outline-color: #ccc;
}
:host([disabled]) > p {
border-color: #ccc;
} ...
</style>
index.html:
<my-element disabled></my-element>
<p>Paragraph in the main
document</p>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
:host([disabled]) {
outline-color: #ccc;
}
:host([disabled]) > p {
border-color: #ccc;
} ...
</style>
index.html:
<my-element></my-element>
<p>Paragraph in the main
document</p>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
</style>
index.html:
<my-element></my-element>
<p>Paragraph in the main
document</p>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
</style>
index.html:
<style>
p { background-color: #9cf; }
</style>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
my-element { outline-color: red; }
</style>
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
</style>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
my-element { outline-color: red; }
my-element p {
border-color: blue;
}
</style>
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
</style>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
</style>
index.html:
<style>
p { background-color: #9cf; }
</style>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
</style>
index.html:
<my-element></my-element>
<p>Paragraph in the main
document</p>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
</style>
index.html:
<my-element>
<ul>
</ul>
</my-element>
<p>Paragraph in the main
document</p>

Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
</style>
index.html:
<my-element>
<ul>
<li>This is Light DOM</li>
<li>It needs a slot</li>
</ul>
</my-element>
<p>Paragraph in the main

my-element.html:
<template>
<style> ... </style>
<p>Shadow DOM is awesome</p>
</template>
Rendered Result:
Shadow DOM is awesome
Paragraph in the main document
index.html:
<my-element>
<ul>
<li>This is Light DOM</li>
<li>It needs a slot</li>
</ul>
</my-element>
<p>Paragraph in the main

my-element.html:
<template>
<style> ... </style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document

my-element.html:
<template>
<style> ... </style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
Flattened DOM Tree:
<body>
<my-element>
#shadow-root (open)
<style>...</style>
<p>Shadow DOM is awesome</p>
<slot>
<ul>
<li>This is Light DOM</li>
<li>It needs a slot</li>
</ul>
</slot>
</my-element> ...

my-element.html:
<template>
<style> ... </style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
Flattened DOM Tree:
<body>
<my-element>
#shadow-root (open)
<style>...</style>
<p>Shadow DOM is awesome</p>
<slot>
<ul>
<li>This is Light DOM</li>
<li>It needs a slot</li>
</ul>
</slot>
</my-element> ...

my-element.html:
<template>
<style> ... </style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document

my-element.html:
<template>
<style>
...
::slotted(ul) {
}
</style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
::slotted() selector

my-element.html:
<template>
<style>
...
::slotted(ul) {
margin: 0;
}
</style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document

my-element.html:
<template>
<style>
...
::slotted(ul) {
margin: 0;
}
::slotted(ul > li) {
color: red;
}
</style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document

my-element.html:
<template>
<style>
...
::slotted(ul) {
margin: 0;
}
</style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document

my-element.html:
<template>
<style>
...
::slotted(ul) {
margin: 0;
}
</style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
</style>

my-element.html:
<template>
<style>
...
::slotted(ul) {
margin: 0;
}
</style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
li { color: red; }
</style>

my-element.html:
<template>
<style>
...
::slotted(ul) {
margin: 0;
}
</style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
ul { color: red; }
</style>

my-element.html:
<template>
<style>
...
::slotted(ul) {
margin: 0;
color: blue;
}
</style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
ul { color: red; }
</style>

my-element.html:
<template>
<style>
...
::slotted(ul) {
margin: 0;
color: blue;
}
</style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
</style>

my-element.html:
<template>
<style>
...
::slotted(ul) {
margin: 0;
color: blue;
}
</style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
</style>

my-element.html:
<template>
<style>
...
::slotted(ul) {
margin: 0;
}
</style>
<p>Shadow DOM is awesome</p>
<slot></slot>
</template>
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
</style>

my-element.html:
<template>
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
::slotted(ul) { ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
</style>

my-element.html:
<template>
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
::slotted(ul) { ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
body { color: green;
font-family: Calibri; }
p { background-color: #9cf; }

my-element.html:
<template>
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
color: initial;
}
p {
border: 3px solid #f60;
margin: 0;
}
::slotted(ul) { ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
body { color: green;
font-family: Calibri; }
p { background-color: #9cf; }

my-element.html:
<template>
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
all: initial;
}
p {
border: 3px solid #f60;
margin: 0;
}
::slotted(ul) { ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
body { color: green;
font-family: Calibri; }
p { background-color: #9cf; }

CSS
Custom Properties"Chameleon" by George is licensed under CC0 1.0

CSS Custom Properties
Basic usage:
<style>
html {
/* Define a Custom Property */
--body-text-color: gray;
}
p {
/* Use a Custom Property */
color: var(--body-text-color);
}
</style>
115 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

CSS Custom Properties
Basic usage:
<style>
html {
/* Define a Custom Property */
--body-text-color: gray;
}
p {
/* Use a Custom Property with a fallback value */
color: var(--body-text-color, navy);
}
</style>
116 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

CSS Custom Properties
Basic usage:
<style>
html {
/* Define a Custom Property */
--body-text-color: gray;
}
p {
/* Use a Custom Property with multiple fallback values */
color: var(--body-text-color, var(--p-text-color, navy));
}
</style>
117 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid #f60;
margin: 0;
}
::slotted(ul) {
margin: 0; ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
</style>

my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
}
::slotted(ul) {
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
p { background-color: #9cf; }
</style>

my-element.html:
<style>
:host {
outline: 3px dashed blue;
display: block;
contain: content;
}
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
}
::slotted(ul) {
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
html { --my-element-border-color:
purple; }
p { background-color: #9cf; }

• Name colors: --xc-blue-sky: #0272B6;
• Set variables for usage: --xc-link-color: var(--xc-blue-sky);
• Useful to name Custom Property hooks in the format of
--element-property: var(--my-element-border-color, #f60);
• Besides colors, gaps and/or padding factors are useful:
--xc-main-gap: 16px; --xc-large-gap: 24px;
padding: var(--xc-main-gap); padding: calc(1.5*var(--xc-main-gap));
CSS Custom Properties Tips
121 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

CSS Mixins"Mix Colorful Color" is licensed under CC0 1.0

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
Import polymer.html or add
shadycss/apply-shim.html

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
Use `@apply` to add the mixin hook

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
Polymer CSS Mixin Format:
<custom-style>
<style>
selector {
--mixin-name: {
/* rules */
};
}
</style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
Polymer CSS Mixin Format:
<custom-style>
<style>
selector {
--mixin-name: {
/* rules */
};
}
</style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
Polymer CSS Mixin Format:
<custom-style>
<style>
selector {
--mixin-name: {
/* rules */
};
}
</style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
Polymer CSS Mixin Format:
<custom-style>
<style>
selector {
--mixin-name: {
}
}
</style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
Polymer CSS Mixin Format:
<custom-style>
<style>
selector {
--mixin-name: {
/* rules */
};
}
</style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
Polymer CSS Mixin Format:
<custom-style>
<style>
selector {
--mixin-name: {
/* rules */
};
}
</style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
Polymer CSS Mixin Format:
<custom-style>
<style>
selector {
--mixin-name: {
/* rules */
};
}
</style>
</custom-style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
html {
--my-element-border-color: purple; }
}
p { background-color: #9cf; }
...
</style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<style>
html {
--my-element-p {
background: red;
font-style: italic;
}; ...
} ... </style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<custom-style> <style>
html {
--my-element-p: {
background: red;
font-style: italic;
}; ...
} ... </style> </custom-style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<custom-style> <style>
html {
--my-element-p: {
background: red;
font-style: italic;
}; ...
} ... </style> </custom-style>
Style in my-element.html after shim is applied:
<style>
p {
border: 3px solid var(--my-element-border-color, #f60);
margin: 0;
background: var(--my-element-p_-_background);
font-style: var(--my-element-p_-_font-style);
}
</style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<custom-style> <style>
html {
--my-element-p: {
background: red;
font-style: italic;
}; ...
} ... </style> </custom-style>
Style in my-element.html after shim is applied:
<style>
p {
border: 3px solid var(--my-element-border-color, #f60);
margin: 0;
background: var(--my-element-p_-_background);
font-style: var(--my-element-p_-_font-style);
}
</style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<custom-style> <style>
html {
--my-element-p: {
background: red;
font-style: italic;
}; ...
} ... </style> </custom-style>
Style in my-element.html after shim is applied:
<style>
p {
border: 3px solid var(--my-element-border-color, #f60);
margin: 0;
background: var(--my-element-p_-_background);
font-style: var(--my-element-p_-_font-style);
}
</style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<custom-style> <style>
html {
--my-element-p: {
background: red;
font-style: italic;
}; ...
} ... </style> </custom-style>
Style in my-element.html after shim is applied:
<style>
p {
border: 3px solid var(--my-element-border-color, #f60);
margin: 0;
background: var(--my-element-p_-_background);
font-style: var(--my-element-p_-_font-style);
}
</style>
Style in index.html after shim is applied:
<custom-style> <style>
html {
--my-element-border-color: purple;
--my-element-p_-_background: red;
--my-element-p_-_font-style: italic;
}
</style> </custom-style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<custom-style> <style>
html {
--my-element-p: {
background: red;
font-style: italic;
}; ...
} ... </style> </custom-style>
Style in my-element.html after shim is applied:
<style>
p {
border: 3px solid var(--my-element-border-color, #f60);
margin: 0;
background: var(--my-element-p_-_background);
font-style: var(--my-element-p_-_font-style);
}
</style>
Style in index.html after shim is applied:
<custom-style> <style>
html {
--my-element-border-color: purple;
--my-element-p_-_background: red;
--my-element-p_-_font-style: italic;
}
</style> </custom-style>

my-element.html:
<link rel="import"
href="bower_components/polymer/
polymer.html">
...
<style> ...
p {
border: 3px solid
var(--my-element-border-color,
#f60);
margin: 0;
@apply --my-element-p;
} ...
Rendered Result:
Shadow DOM is awesome
• This is Light DOM
• It needs a slot
Paragraph in the main document
index.html:
<custom-style> <style>
html {
--my-element-p: {
background: red;
font-style: italic;
}; ...
} ... </style> </custom-style>
Style in my-element.html after shim is applied:
<style>
p {
border: 3px solid var(--my-element-border-color, #f60);
margin: 0;
background: var(--my-element-p_-_background);
font-style: var(--my-element-p_-_font-style);
}
</style>
Style in index.html after shim is applied:
<custom-style> <style>
html {
--my-element-border-color: purple;
--my-element-p_-_background: red;
--my-element-p_-_font-style: italic;
}
</style> </custom-style>

• Used for setting styles in the main document, either:
- Declared directly in the main document, or
- Hoisted to the main document from an import
• When would you want to include them in an import?
- @font-face rules
- Theming (declaring common variables & mixins)
• <custom-style> & @apply can be loaded on their own via
ShadyCSS (see https://github.com/webcomponents/shadycss)
More <custom-style> notes
143 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

• This warning is unavoidable when using <custom-style>:
• If you’re using at least Polymer 1.10.1 or 2.1.1, you’re good
More <custom-style> notes
144 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

• Style Modules are Polymer’s way of sharing styles among
Polymer Components
• The styles are actually copied into the Shadow Root of the
component they are included in
- So only include what you actually need
• Great way of sharing form element styles like buttons
Another way to share styles: Style Modules
145 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

my-button-styles.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-button-styles">
<template>
<style>
button {
background: #fff;
border: 3px solid rebeccapurple;
color: rebeccapurple;
text-decoration: none;
}
button:hover {
background: rebeccapurple; color: #fff;
}
button:focus {
color: navy; background: powderblue;
}
</style>
</template>
</dom-module>

my-button-styles.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-button-styles">
<template>
<style>
button {
background: #fff;
border: 3px solid rebeccapurple;
color: rebeccapurple;
text-decoration: none;
}
button:hover {
background: rebeccapurple; color: #fff;
}
button:focus {
color: navy; background: powderblue;
}
</style>
</template>
</dom-module>
Declare styles in a dom-module with an `id` attribute

my-button-styles.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-button-styles">
<template>
<style>
button {
background: #fff;
border: 3px solid rebeccapurple;
color: rebeccapurple;
text-decoration: none;
}
button:hover {
background: rebeccapurple; color: #fff;
}
button:focus {
color: navy; background: powderblue;
}
</style>
</template>
</dom-module>
my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<link rel="import" href="my-button-styles.html">
<dom-module id="my-element">
<template>
<style include="my-button-styles">
/* Element-specific CSS goes here */
</style>
...
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>

my-button-styles.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-button-styles">
<template>
<style>
button {
background: #fff;
border: 3px solid rebeccapurple;
color: rebeccapurple;
text-decoration: none;
}
button:hover {
background: rebeccapurple; color: #fff;
}
button:focus {
color: navy; background: powderblue;
}
</style>
</template>
</dom-module>
my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<link rel="import" href="my-button-styles.html">
<dom-module id="my-element">
<template>
<style include="my-button-styles">
/* Element-specific CSS goes here */
</style>
...
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
Import the styles

my-button-styles.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-button-styles">
<template>
<style>
button {
background: #fff;
border: 3px solid rebeccapurple;
color: rebeccapurple;
text-decoration: none;
}
button:hover {
background: rebeccapurple; color: #fff;
}
button:focus {
color: navy; background: powderblue;
}
</style>
</template>
</dom-module>
my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<link rel="import" href="my-button-styles.html">
<dom-module id="my-element">
<template>
<style include="my-button-styles">
/* Element-specific CSS goes here */
</style>
...
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
Include the styles

my-button-styles.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<dom-module id="my-button-styles">
<template>
<style>
button {
background: #fff;
border: 3px solid rebeccapurple;
color: rebeccapurple;
text-decoration: none;
}
button:hover {
background: rebeccapurple; color: #fff;
}
button:focus {
color: navy; background: powderblue;
}
</style>
</template>
</dom-module>
my-element.html:
<link rel="import"
href="bower_components/polymer/polymer-element.html">
<link rel="import" href="my-button-styles.html">
<dom-module id="my-element">
<template>
<style include="my-button-styles">
/* Element-specific CSS goes here */
</style>
...
</template>
<script>
class MyElement extends Polymer.Element {
static get is() { return 'my-element'; }
}
window.customElements.define(MyElement.is,
MyElement);
</script>
</dom-module>
Add additional CSS here

ShadyCSS Shim Limitations
• ::slotted needs a selector before it (such as :host)
• External stylesheets within a shadow root cannot be shimmed
- So no <link rel="stylesheet"> or @import
• Avoid dynamic changes, including:
- Changing a custom property value
- Adding styles after the scoping shim is executed
153
Additional Details: https://github.com/webcomponents/shadycss#limitations
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

"scroll-1410168" is licensed under CC0 1.0

Documenting Your Polymer Code
• Document with JSDoc syntax - usejsdoc.org
• Create a page that imports & includes iron-component-page
• Generate the docs and load your page:
$ npm i -g polymer-cli bower
$ polymer analyze > analysis.json
$ polymer serve --open
155
Additional Details: https://github.com/PolymerElements/iron-component-page
Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

<!--
Material design:
[Tabs](https://www.google.com/design/s
pec/components/tabs.html)
`paper-tabs` makes it easy to explore
and switch between different views or
functional aspects of
an app, or to browse categorized data
sets.
Use `selected` property to get or set
the selected tab.
Example:
<paper-tabs selected="0">
<paper-tab>TAB 1</paper-tab>
<paper-tab>TAB 2</paper-tab>
<paper-tab>TAB 3</paper-tab>
</paper-tabs>

<!--
### Styling
The following custom properties and
mixins are available for styling:
Custom property | Description |
Default
----------------|-------------|-------
---
`--paper-tabs-selection-bar-color` |
Color for the selection bar | `--
paper-yellow-a100`
`--paper-tabs-selection-bar` | Mixin
applied to the selection bar | `{}`
`--paper-tabs` | Mixin applied to the
tabs | `{}`
`--paper-tabs-content` | Mixin applied
to the content container of tabs |
`{}`
`--paper-tabs-container` | Mixin
applied to the layout container of

/**
* If true, the tabs are aligned
to bottom (the selection bar
appears at the top).
*/
alignBottom: {
type: Boolean,
value: false
},
/**
* If true, tabs are
automatically selected when
focused using the
* keyboard.
*/
autoselect: {
type: Boolean,
value: false
},

Demo
Driven
Development

© Comcast

Source: https://github.com/webcomponents/gold-standard/wiki

MONO
REPO
MANY
REPOS
MONO
REPO
MANY
REPOS
vs.
"Peñón de Ifach - Calpe - Spain" by Wyemji is licensed under CC BY-SA 3.0 "Mohegan Bluffs" by John Riviello is licensed under CC BY-SA 2.0

How do teams use my
Polymer-Powered
Design System?

{
"name": "my-app",
"flat": true,
...
http://yarnpkg.com
Why Yarn & not NPM? See https://github.com/package-community/discussions/issues/2

Using Web Components
• Import the component
- <link rel="import" href="https://your-web-component-
cdn.com/iron-pages/iron-pages.html">
• Use your custom element as a normal HTML tag
- <iron-pages>
<div>Page 1 content</div>
<div>Page 2 content</div>
</iron-pages>
171 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

© Comcast

© Comcast

<script href="https://polaris.xfinity.com/polaris.js"></script>
<xc-header
tab="myaccount"
is-authed="[[isAuthed]]"
login-url="/login"
sign-out-url="/logout"
first-name="[[openidData.given_name]]"
user-name="[[openidData.preferred_username]]">
</xc-header>
<xc-footer></xc-footer>
View the Open Source code at https://github.com/Comcast/polaris
174 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

Polymer-Powered Design Systems
• Have a team of designers & developers
responsible for your design system
• Polymer & Web Components are a great way to
build reusable components that work across
multiple frameworks
• Don’t forget your colons & semicolons when
defining Polymer CSS Mixins
• Embrace Demo Driven Development
175 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

Useful Links
• WebComponents.org - webcomponents.org
• Polymer Website - polymer-project.org
• Polymer Slack - polymer-slack.herokuapp.com
• Polymer 2.x Cheat Sheet - https://meowni.ca/posts/polymer-2-cheatsheet/
• How to use Polymer with Webpack - http://robdodson.me/how-to-use-polymer-with-webpack/
• PWAs with Polymer: a checklist - https://meowni.ca/posts/polymer-pwa-checklist/
• Custom Elements Everywhere - https://custom-elements-everywhere.com/
• Polycasts on YouTube -
https://www.youtube.com/playlist?list=PLOU2XLYxmsII5c3Mgw6fNYCzaWrsM3sMN
• 2017 Polymer Summit videos on YouTube -
https://www.youtube.com/playlist?list=PLNYkxOF6rcIDP0PqVaJxqNWwIgvoEPzJi
• End-to-End Polymer Apps - 2017 Chrome Dev Summit video - https://youtu.be/Wu2GCRkDecI
• 2017 Google I/O Polymer videos on YouTube -
https://www.youtube.com/playlist?list=PL_c6rbXV248du6m1VJABo32mP7sXWVb4m
176 Ensuring Design Standards with Web Components - @JohnRiv @chiefcll

Thank you!
John Riviello
@JohnRiv
Chris Lorenzo
@Chiefcll