project uses typescript to statically analyze code
project uses eslint 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 plugin to be installed.

although styles have scss extension, it is actually pack of post-css plugins, so syntax differs, for example in calc function.
component styles use BEM notation (at least it should): block__element_modifier. Also there are mix classes: block_modifier.
component base style resides in the component's root directory with name of component converted to kebab-case. For example ListComments style is located in ./app/components/list-comments/list-comments/scss
component's element style resides in its own subdirectory, with name consisting of full elements selector, for example ListComments item element is placed in __item directory under name ./list-comments__item.scss
each style should be required in index.ts of component's root directory

imports for typescript, javascript files should be without extension: ./index, not ./index.ts
if file resides in same directory or in subdirectory import should be relative: ./types/something
otherwise it should start from @app namespace: @app/common/store which mapped to /app/common/store.ts in webpack, tsconfig and jest

project uses jest as test harness.
jest check files that match regex \.test\.(j|t)s(x?)$, i.e comment.test.tsx, comment.test.js
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

add new item to ./tasks/supportedLocales.json
run npm run generate-langs
commit all changed files
translate all string in new generated dictionary ./app/locale/<new-locale>.json

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