Dmitry VerkhoturovandGitHub
a5b2fe3cfc
Four upgrades that were finished but never merged, the compiler collapse
they enable, and the dependency sweep that follows. Direct
devDependencies go from 78 to 60 and dependencies from 10 to 9.
Three were doing the same job: `ts-loader` stripped types in webpack,
`babel-loader` did everything else, and `@swc/jest` repeated both for the
tests with its own copy of the JSX settings. Babel is the one that
survives, because the `data-testid` stripper has no equivalent elsewhere.
`ts-loader` ran `transpileOnly: true`, so it only stripped types, which
`@babel/preset-typescript` does; `fork-ts-checker-webpack-plugin` was
already what type-checks. Jest runs `babel-jest` against the same
`.babelrc.js` the bundle uses, passed as `configFile` because a
file-relative babel config does not reach the `node_modules` packages in
`transformIgnorePatterns`, and `jest.config.mjs` is plain ESM because a
`.ts` config is compiled against `tsconfig.json`, whose
`verbatimModuleSyntax` rejects ESM syntax in a file the package has not
declared as a module.
That removes `ts-loader`, `@swc/jest` and `@swc/core`. The last was
pinned to 1.2.205 from 2022 with no way forward, because newer builds
emit non-configurable exports and break `jest.spyOn` across 13 suites.
Babel compiles a file at a time with no type information, so it cannot
tell a type-only import from a real one and keeps the module. One line,
`import { boundActions } from './connected-comment'`, pulled the whole
redux store into `last-comments.mjs` and doubled it. `verbatimModuleSyntax`
and `@typescript-eslint/consistent-type-imports` mark them properly; the
statement has to be a separate `import type`, since verbatim semantics
keep an inline `import { type X }` and load the module anyway.
The legacy and modern compilations produced the same bytes. Both read the
same browserslist query, `defaults, not IE 11, not samsung 12` resolves to
chrome 109 and up, and nothing in the source needs transforming for that
set, so 28 of the 29 output pairs were byte-identical.
That made the module/nomodule switch worse than redundant: it served the
`.js` file to browsers with no ES module support, and those files carried
`??`, `?.` and class fields, so the fallback handed its own audience a
syntax error. There is now one bundle, always loaded as a module, in the
five templates and in the seven `site/` documents integrators copy from.
A production build emits 29 files rather than 58, in about 3 seconds
rather than 17. Two of those documents did not work at all beforehand:
the SPA snippet could not parse, and the subdomain example had an
unterminated string.
`@babel/core` 8 declares `^22.18 || >=24.11` and `size-limit` 13 declares
`^22.18 || ^24 || >=26`, so 20 was below the floor of two things installed
here; pnpm only warns, which is why every build passed. All seven places
the frontend pins it move together. `site/` is untouched: it builds with
yarn and eleventy and installs neither.
`eslint --print-config` before and after gives 173 active rules on an
application file against 172, and 172 on a spec file and a plain JS file
against 171. What is gone is three `flowtype` rules with no Flow here,
`no-new-object` and `no-new-symbol` whose upstream replacements are on,
`react/forbid-foreign-prop-types` with no propTypes anywhere, and, on TS
only, `no-useless-constructor`, whose typescript-eslint version is on at
error. `@babel/core` is pinned to 8 across the workspace because
`@jest/transform` and `istanbul-lib-instrument` depend on 7 outright; a
second scoped override holds `eslint-config-preact` on 7, since its
`@babel/eslint-parser` loads babel 7 syntax plugins.
`fast-async` rewrote every async function into nodent promise chains,
calls babel's `transform` synchronously, which babel 8 removed, and every
browser in the target list runs async natively. `prefresh` blew its stack
on `createContext` under babel 8 with no newer release to move to, which
compiled `intl.tsx` and `store/context.tsx` into throwing stubs, so
`pnpm dev:app` could not run the widget at all. `core-js` is not injected
now that `useBuiltIns` is gone, `postcss-custom-properties` was reached
directly although nothing declared it and resolved only through pnpm's
private hoist directory, and `cssnano` ran in both postcss chains although
`CssMinimizerPlugin` already uses it.
`pnpm lint`, `pnpm test` and `pnpm build` now work from `frontend/` as
`CLAUDE.md` and the contributing guide have always said they do; the
workspace root defined none of them.
8.1 KiB
title
| title |
|---|
| Frontend Development Guidelines |
Prerequisites
Frontend for Remark42 is built with Preact and Redux.
{{< note "💡" >}}
We highly recommend checking out Preact documentation.
React libraries are not usable here: the store bindings and the i18n helpers are small local
modules under app/.
{{< /note >}}
In order to inject Remark42 widgets into websites we use iframe and postMessage for communication between a site and the widget.
Simple widgets like counter widget can be injected as a script because it doesn't have its own interface.
While developing, we set up environment which imitates real world example. We serve the page which uses Remark42 config and inject all the widgets on it. You can check it on our demo site. After successful installation you should have the same page running locally.
Installation
You must have at least 2GB RAM or swap enabled for building.
- install Node.js 24 or higher (we recommend using NVM for node version autoswitch)
- install PNPM 10
- run
pnpm iinside./frontend
Running pnpm i will set up pre-commit hooks into your git repository. They are used to reformat your frontend code using prettier and lint with eslint and stylelint before every commit.
{{< note "🚨" >}}
Please use 127.0.0.1 and not localhost to access the server; otherwise, CORS will prevent your browser from authentication to work correctly. You could alter the address for dev auth with the REMARK_URL environment variable.
{{< /note >}}
Development
Run frontend with remote backend
You can run frontend against demo instance of Remark42. This method of running Remark42 frontend code is preferred when you make a translation or visual adjustments that are easy to see without extensive testing. For this method we use our demo instance of Remark42 served on https://demo.remark42.com
For local development mode with Hot Reloading, use pnpm dev:app. In this case, webpack will serve files using webpack-dev-server on 127.0.0.1:9000. By visiting http://127.0.0.1:9000/web/, you will get a page with the main comments' widget communicating with a demo server backend running on https://demo.remark42.com. But you will not be able to log in with any OAuth providers due to security reasons.
You can attach the frontend to the locally running backend from frontend/apps/remark42 folder and providing the REMARK_URL environment variable.
npx cross-env REMARK_URL=http://127.0.0.1:8080 pnpm dev:custom
{{< note "ℹ️" >}}
If you want to redefine env variables such as PORT on your local instance, you can add the .env file to the ./frontend folder and rewrite variables as you wish. For such functional, we use dotenv.
{{< /note >}}
Run frontend with backend locally
This option of running Remark42 frontend code is preferred when you need extensive testing of your code changes, as you'll have your backend and configure it as you want, for example, enable any auth and notifications method you need to test. You can use that set up to develop and test both frontend and backend.
To bring the backend up, run:
cp compose-dev-frontend.yml compose-private.yml
# now, edit / debug `compose-private.yml` to your heart's content
# build and run
docker compose -f compose-private.yml up --build
Then in the new terminal tab or window, run the following to start the frontend with Hot Reloading:
cd frontend
pnpm dev:app
Developer build running by webpack-dev-server supports devtools for React and Redux.
It starts Remark42 backend on 127.0.0.1:8080 and adds local OAuth2 provider "Dev". To access the frontend running by Node, go to http://127.0.0.1:9000/web/. By default, you would be logged in as dev_user, defined as admin. You can tweak any of the supported parameters in corresponded yml file.
Manual testing after changes
Frontend Docker Compose config (compose-dev-frontend.yml) by default skips running backend related tests.
{{< note "🚨" >}}
Before submitting your changes as a Pull Request, run the backend using the docker compose -f compose-dev-frontend.yml build --build-arg SKIP_FRONTEND_BUILD=""; docker compose -f compose-private.yml up command and test your changes against http://127.0.0.1:8080/web/, frontend, built statically (unlike frontend on port 9000, which runs dynamically). That is how Remark42 authors will test your changes once you submit them.
{{< /note >}}
Static build
Remark42 frontend can be built statically, and that's how the production version works: frontend is built and then resulting files embedded into the backend, which serves them as-is. Node is not running when a user starts Remark42, only the backend written in Go programming language, which also serves pre-built frontend HTML and JS and CSS files.
Run pnpm build inside ./frontend, and result files will be saved in ./frontend/apps/remark42/public.
/web is served from two sources. This build output comes first; anything it does not emit is
served from backend/app/webassets/assets, embedded in the backend binary, which is where
privacy.html, markdown-help.html and 400x400.jpeg live. A plain page or image the bundler
does not process belongs there rather than here. Those files sit outside the frontend toolchain,
so prettier, stylelint and pnpm lint do not see them.
Code Style
- The project uses TypeScript to analyze code statically
- The project uses Eslint and Stylelint to check the frontend code. You can manually run via
pnpm lint - Git Hooks (via husky) installed automatically on
pnpm i. They check and try to fix code style if possible, otherwise commit will be rejected - If you want IDE integration, you need Eslint and Stylelint plugins to be installed. Eslint reads
eslint.config.mjsfrom the directory it is run in, so point your editor at the app directory: for VSCode,"eslint.workingDirectories": ["frontend/apps/remark42"]
CSS Styles
- Now we are migrating to CSS Modules, which is a recommended way of 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 aremixclasses:block_modifier - The new way to name CSS selectors is camel-case like
blockElemenModifierand useclsxto combine it - Component base style resides in the component's root directory with a name of component converted to kebab-case. For example,
ListCommentsstyle is located in./app/components/list-comments/list-component.tsx - Any other files should also be named 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, the import should be relative:
./types/something - Otherwise, it should be imported by absolute path relative to
srcfolder likecommon/storewhich mapped to./app/common/store.tsin webpack, tsconfig, and Jest
Testing
- Project uses Jest as test framework
- Testing Library is used for UI tests
- 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/components/auth/auth.spec.tsx,./app/store/user/reducers.test.ts
Notes
Frontend part being bundled on docker env gets placed on /src/web and is available via http://{host}/web. For example, embed.mjs entry point will be available at http://{host}/web/embed.mjs