84 lines
2.9 KiB
Markdown
84 lines
2.9 KiB
Markdown
# LitElement TypeScript starter
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This project includes a sample component using LitElement with TypeScript.
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## Setup
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Install dependencies:
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```bash
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npm i
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```
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## Build
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This sample uses the TypeScript compiler to produce JavaScript that runs in modern browsers.
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To build the JavaScript version of your component:
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```bash
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npm run build
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```
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To watch files and rebuild when the files are modified, run the following command in a separate shell:
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```bash
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npm run build:watch
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```
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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.
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## Testing
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This sample uses Karma, Chai, Mocha, and the open-wc test helpers for testing. See the [open-wc testing documentation](https://open-wc.org/testing/testing.html) for more information.
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Tests can be run with the `test` script:
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```bash
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npm test
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```
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## Dev Server
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This sample uses open-wc's [es-dev-server](https://github.com/open-wc/open-wc/tree/master/packages/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.
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To run the dev server and open the project in a new browser tab:
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```bash
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npm run serve
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```
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## Editing
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If you use VS Code, we highly reccomend the [lit-plugin extension](https://marketplace.visualstudio.com/items?itemName=runem.lit-plugin), which enables some extremely useful features for lit-html templates:
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- Syntax highlighting
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- Type-checking
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- Code completion
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- Hover-over docs
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- Jump to definition
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- Linting
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- Quick Fixes
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The project is setup to reccomend lit-plugin to VS Code users if they don't already have it installed.
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## Linting
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Linting of TypeScript files is provided by [ESLint](eslint.org) and [TypeScript ESLint](https://github.com/typescript-eslint/typescript-eslint). In addition, [lit-analyzer](https://www.npmjs.com/package/lit-analyzer) is used to type-check and lint lit-html templates with the same engine and rules as lit-plugin.
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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`.
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To lint the project run:
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```bash
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npm run lint
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```
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## Formatting
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[Prettier](https://prettier.io/) is used for code formatting. It has been pre-configured according to the Polymer Project's style. You can change this in `.prettierrc.json`.
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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](https://prettier.io/) site for instructions.
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## More information
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See [Get started](https://lit-element.polymer-project.org/guide/start) on the LitElement site for more information.
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