Learn POLYMER with Real Code Examples

Install Polymer CLI globally: `npm install -g polymer-cli`

Create a new project: `polymer init`

Install dependencies via npm

Serve with: `polymer serve`

Build with: `polymer build`

Install Node.js and npm

Install Polymer CLI: `npm install -g polymer-cli`

Enable ES Modules in browser

Set up a local dev server

Verify setup with `polymer --version`

polymer.json - project config

package.json - dependencies

index.html - entry point

src/*.js - components

shared-styles.js - shared styling modules

polymer init - create a new project

polymer serve - dev server

polymer build - production build

polymer lint - lint components

polymer test - run tests

Use libraries like `@polymer/app-localize-behavior`

JSON-based message files

Locale switching support

Template-bound translations

Compatibility with global i18n libraries

ARIA roles inside custom elements

Keyboard navigation support

Shadow DOM accessibility considerations

Lighthouse audits

Semantic HTML inside templates

Shadow DOM encapsulated styling

CSS custom properties

Shared style modules

Theming with design tokens

Scoped styles inside templates

Local component state

Property observers

Parent–child communication via events

Global state via custom libraries

Integration with Redux if needed

One-way and two-way data binding

Observed properties

Computed properties

API calls via Fetch/Axios

Use of LitElement for better state management patterns