This project includes a sample component using LitElement with TypeScript.
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Install dependencies:
npm i
This sample uses the TypeScript compiler to produce JavaScript that runs in modern browsers.
To build the JavaScript version of your component:
npm run build
To watch files and rebuild when the files are modified, run the following command in a separate shell:
npm run build:watch
Both the TypeScript compiler and lit-analyzer are configured to be very strict. You may want to change tsconfig.json
to make them less strict.
This sample uses Karma, Chai, Mocha, and the open-wc test helpers for testing. See the open-wc testing documentation for more information.
Tests can be run with the test
script:
npm test
This sample uses open-wc's es-dev-server for previewing the project without additional build steps. ES dev server handles resolving Node-style "bare" import specifiers, which aren't supported in browsers. It also automatically transpiles JavaScript and adds polyfills to support older browsers.
To run the dev server and open the project in a new browser tab:
npm run serve
There is a development HTML file located at /dev/index.html
that you can view at http://localhost:8000/dev/index.html.
If you use VS Code, we highly reccomend the lit-plugin extension, which enables some extremely useful features for lit-html templates:
- Syntax highlighting
- Type-checking
- Code completion
- Hover-over docs
- Jump to definition
- Linting
- Quick Fixes
The project is setup to reccomend lit-plugin to VS Code users if they don't already have it installed.
Linting of TypeScript files is provided by ESLint and TypeScript ESLint. In addition, lit-analyzer is used to type-check and lint lit-html templates with the same engine and rules as lit-plugin.
The rules are mostly the recommended rules from each project, but some have been turned off to make LitElement usage easier. The recommended rules are pretty strict, so you may want to relax them by editing .eslintrc.json
and tsconfig.json
.
To lint the project run:
npm run lint
Prettier is used for code formatting. It has been pre-configured according to the Polymer Project's style. You can change this in .prettierrc.json
.
Prettier has not been configured to run when commiting files, but this can be added with Husky and and pretty-quick
. See the prettier.io site for instructions.
This project includes a simple website generated with the eleventy static site generator and the templates and pages in /docs-src
. The site is generated to /docs
and intended to be checked in so that GitHub pages can serve the site from /docs
on the master branch.
To enable the site go to the GitHub settings and change the GitHub Pages "Source" setting to "master branch /docs folder".
To build the site, run:
npm run docs
To serve the site locally, run:
npm run docs:serve
To watch the site files, and re-build automatically, run:
npm run docs:watch
The site will usually be served at http://localhost:8000.
See Get started on the LitElement site for more information.