JavaScript practices

While JavaScript is useful to make complex data entry and interaction tasks easier, there is value in maintaining a functional plain HTML interface, and in modern browsers, HTML plus CSS interfaces can go a long way.

When there is a UI task, like sorting a list, which would have a significantly better UI with the help of JavaScript, we can do it via incremental improvement, with a basic HTML interface that is hidden when JavaScript is enabled, and replaced with a different scripted one.

Data submitted from data entry enhanced with JavaScript should match the form data submitted with the HTML-only form inputs, so that server-side validation and handling can be reused for both.

In those cases where a UI task is not at all possible without JavaScript, we can make its support mandatory as long as the same goal can be otherwise achieved using the debusine client command.

Target browsers

We target the main browsers shipped in Debian stable, and oldstable as long as it’s still officially supported by Debian.

As of September 2025, this means firefox-esr 115 and chrome 135.

We are therefore allowed to use:

• The full ECMAScript 2015 featureset

• CSS3, with the attr() function limited to the content property

Modules

We use JavaScript modules <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules> to structure our code. The web/_base.html base template defines an importmap that can be extended by other templates.

Linting and formatting

We do not yet have infrastructure to lint and format JavaScript code.

Testing

We do not yet have infrastructure to perform unit testing and functional testing of JavaScript code, and we rely on manual testing.