Frontend

The Warehouse frontend is (as you might suspect) written in JavaScript with the CSS handled by SCSS. It uses gulp to process these files and prepare them for serving.

All of the static files are located in warehouse/static/ and external libraries are found in package.json.

Building

Static files should be automatically built when make serve is running; however, you can trigger a manual build of them by installing NodeJS 8.x, installing the dependencies using npm install and then running gulp dist.

If you’re in a POSIX enviroment you may find NVM useful to have multiple NodeJS versions installed in your system.

Tests

The JavaScript codebase includes tests that can be ran via make static_tests which is also ran with the make tests target. Both targets will run the tests in the Docker enviroment but they may also be ran locally using npm run test once NodeJS and the dependencies are installed as described above.

JavaScript tests use the Jest testing framework along with jest-dom for assertion helpers. We can invoke Jest directly specify a particular test suite via node_modules/.bin/jest tests/frontend/<TEST_FILE>.js or add any of the Jest CLI options . All tests are located in the tests/frontend.

Stimulus controller tests leverage on Jest including JSDOM allowing us to inject the required HTML markup for Stimulus in a setup phase. After the setup we must manually instanciate and start a Stimulus application and then test the funcionality by triggering events in DOM elements and asserting on the effects. See existing tests the details on how to accomplish this.

Note

This workflow may cause race conditions, in particular when testing code in the early lifecycle events of the controllers. The application or controller may not be ready by the time we reach the assertions causing false negatives on the tests. In these cases it’s best to keep the HTML setup in a beforeEach block, even if it means repeating the setup on different describe scenarios. This will ensure the application and controllers are ready before the actual test is ran.

Deploying

When deploying changes to the frontend, to see the changes immediately it is necessary to purge the cache.

Individual pages can be purged from the command line by issuing a XPURGE request, e.g.:

curl -XPURGE https://pypi.org/the/page/to/purge

All HTML pages can be dropped from the cache by purging the all-html surrogate key via our CDN provider.

The entire cache can be purged by issuing a “Purge All” via our CDN provider.

Purging the cache is not usually necessary when making frontend changes, unless it would be unacceptable for the site to simultaneously have an “old” version of some pages, but the “new” version of others.

Browser Support

Browser Supported Versions
Chrome Current, Current - 1
Firefox Current, Current - 1
Edge Current, Current - 1
Opera Current, Current - 1
Safari 9.0+
IE 11+

HTML Code Style

Warehouse follows the Google HTML style guide, which is enforced via linting with HTML Linter.

Exceptions to these rules include:

  • Protocols can be included in links - we prefer to include https protocols
  • All HTML tags should be closed

We also allow both dashes and underscores in our class names, as we follow the Nicholas Gallagher variation of the BEM naming methodology.

More information on how BEM works can be found in this article from CSS Wizardry.

When using target="_blank_" for a hyperlink (usually to an external site), we should always set rel="noopener".

SCSS Style and Structure

Warehouse follows the Airbnb CSS/Sass style guide, with the exception that JS hooks should be prefixed with -js rather than js.

Our SCSS codebase is structured according to the ITCSS system. The principle of this system is to break SCSS code into layers and import them into a main stylesheet in an order moving from generic to specific. This tightly controls the cascade of styles.

The majority of the SCSS styles are found within the ‘blocks’ layer, with each BEM block in its own file. All blocks are documented at the top of the file to provide guidelines for use and modification.

One of these blocks provides code syntax highlighting, which can be tested with reference project provided at http://localhost/project/pypi-code-highlighting-demo/ when using development database. Source reStructuredText file is available here.