Learn POLYMER with Real Code Examples

Reusable button Web Component

Encapsulated card component with Shadow DOM

Framework-agnostic widget for embedding

SPA with routing using `app-route`

Design system built entirely with Web Components

Check if custom element is registered correctly

Verify polyfills for old browsers

Ensure template is returned inside `static get template()`

Debug Shadow DOM styling issues

Check property definitions and observers

Use Web Component Tester for unit tests

Mock component properties

Test Shadow DOM rendering

Run integration tests with Karma

Test events and custom element lifecycle

Build with Polymer CLI

Deploy static files to Firebase Hosting

Deploy to Netlify, Vercel, GitHub Pages

Serve custom elements inside any web app

Bundle with Rollup or Webpack if needed

Polymer CLI

Web Component Tester (WCT)

LitElement (successor framework)

ES Modules tooling

Chrome DevTools for Web Components debugging

Works with any framework (React, Vue, Angular)

Supports npm-based workflows

GraphQL/Apollo for advanced apps

Routing via app-route

Testing: WCT, Mocha, Karma

Use Polymer CLI for quick scaffolding

Keep components small and modular

Use shared CSS modules

Leverage custom events for decoupling

Prefer LitElement for modern builds

Build a reusable `<my-card>` component

Create a form with data binding

Implement routing in a Polymer SPA

Publish a Web Component to npm

Build a mini design system