designsystem_kevin v0.0.7

Stencil Notes Kevin

• The dist-custom-elements-bundle output target is used to generate custom elements as a single bundle. Even though the output ends up as a "single" bundle, it's generated to ensure components are tree-shakable. For example, if a component library has 100 components, but an external project only imported one component from the bundle, then only the code used by that one component would be pulled into the project. This is due to Stencil's use of ES Modules and the compiler generating friendly code for bundlers to parse and understand.

• If a component is dependent on other components, you'll need to register each one manually. This can be tedious so, for convenience, the bundle also exports a defineCustomElements() method.

When defineCustomElements() is called, it will define every component in the bundle. However, it does not run automatically and it will not be called if it is not imported and executed. It can also result in a larger bundle size if there are unused components being imported.

Bundling

• Stencil uses Rollup under the hood to bundle your components. This guide will explain and recommend certain workarounds for some of the most common bundling issues you might encounter.

• For Stencil to bundle your components most efficiently, you must declare a single component (class decorated with @Component) per TypeScript file, and the component itself must have a unique export. By doing so, Stencil is able to easily analyze the entire component graph within the app, and best understand how components should be bundled together. Under-the-hood it uses the Rollup bundler to efficiently bundled shared code together. Additionally, lazy-loading is a default feature of Stencil, so code-splitting is already happening automatically, and only dynamically importing components which are being used on the page.

• By default, Stencil will statically analyze the application and generate a component graph of how all the components are interconnected. From the component graph it is able to best decide how components should be grouped depending on their usage with one another within the app. By doing so it's able to bundle components together in order to reduce network requests. However, bundles can be manually generated using the bundles config.

The bundles config is an array of objects that represent how components are grouped together in lazy-loaded bundles. This config is rarely needed as Stencil handles this automatically behind the scenes.

Testing

• In this project we use testcafe for the e2e test and we use jest for the unit tests.

Stencil Component Starter

This is a starter project for building a standalone Web Component using Stencil.

Stencil is also great for building entire apps. For that, use the stencil-app-starter instead.

Stencil

Stencil is a compiler for building fast web apps using Web Components.

Stencil combines the best concepts of the most popular frontend frameworks into a compile-time rather than run-time tool. Stencil takes TypeScript, JSX, a tiny virtual DOM layer, efficient one-way data binding, an asynchronous rendering pipeline (similar to React Fiber), and lazy-loading out of the box, and generates 100% standards-based Web Components that run in any browser supporting the Custom Elements v1 spec.

Stencil components are just Web Components, so they work in any major framework or with no framework at all.

Getting Started

To start building a new web component using Stencil, clone this repo to a new directory:

git clone https://github.com/ionic-team/stencil-component-starter.git my-component
cd my-component
git remote rm origin

and run:

npm install
npm start

To build the component for production, run:

npm run build

To run the unit tests for the components, run:

npm test

Need help? Check out our docs here.

Naming Components

When creating new component tags, we recommend not using stencil in the component name (ex: <stencil-datepicker>). This is because the generated component has little to nothing to do with Stencil; it's just a web component!

Instead, use a prefix that fits your company or any name for a group of related components. For example, all of the Ionic generated web components use the prefix ion.

Using this component

There are three strategies we recommend for using web components built with Stencil.

The first step for all three of these strategies is to publish to NPM.

Script tag

• Put a script tag similar to this <script src='https://unpkg.com/my-component@0.0.1/dist/mycomponent.js'></script> in the head of your index.html
• Then you can use the element anywhere in your template, JSX, html etc

Node Modules

• Run npm install my-component --save
• Put a script tag similar to this <script src='node_modules/my-component/dist/mycomponent.js'></script> in the head of your index.html
• Then you can use the element anywhere in your template, JSX, html etc

In a stencil-starter app

• Run npm install my-component --save
• Add an import to the npm packages import my-component;
• Then you can use the element anywhere in your template, JSX, html etc