# Frontend guide

### Code Style

* project uses TypeScript to statically analyze code
* project uses `eslint` and `stylelint` to check frontend code. You can manually run via `npm run lint`
* Git Hooks (via husky) installed automatically on `npm install` and check and try to fix code style if possible, otherwise commit will be rejected
* if you want IDE integration, you need `eslint` and `stylelint` plugin to be installed

### CSS Styles

* now we are migrating to CSS Modules and this is a recommended way to stylization. A file with styles should be named like `component.module.css`
* old component styles use BEM notation (at least it should): `block__element_modifier`. Also, there are `mix` classes: `block_modifier`
* new way to naming CSS selectors is camel-case like `blockElemenModifier` and use `classnames` to combine it
* component base style resides in the component's root directory with a name of component converted to kebab-case. For example, `ListComments` style is located in `./app/components/list-comments/list-component.tsx`
* any other files should be named also in kebab-case. For example, `./app/utils/get-param.ts`

### Imports

* imports for TypeScript, JavaScript files should be without extension: `./index`, not `./index.ts`
* if the file resides in the same directory or subdirectory import should be relative: `./types/something`
* otherwise it should be imported by absolute path relative to `src` folder like `common/store` which mapped to `./app/common/store.ts` in webpack, tsconfig and Jest

### Testing

* project uses `jest` as test harness
* Jest checks files that match regex `\.(test|spec)\.ts(x?)$`, i.e. `comment.test.tsx`, `comment.spec.ts`
* tests are running on push attempt
* example tests can be found in `./app/store/user/reducers.test.ts`, `./app/components/auth-panel/auth-panel.test.tsx`

### How to add new locale

Please see [this documentation](/site/src/docs/contributing/translations/index.md).

### Notes

* frontend part being bundled on docker env gets placed on `/src/web` and is available via `http://{host}/web`. For example, `embed.js` entry point will be available at `http://{host}/web/embed.js`