Feature: Enhance a11y

[mlmoravek]

Description

• Add eslint-plugin-vuejs-accessibility
• Add "plugin:vuejs-accessibility/recommended" eslint rule.
• Update all components to fullfill the recommended a11y rules.

Why Oruga need this feature

Accessibility is a big topic and a component library should implement a11y support by default as good as they can.

[mmazanec22]

I'm using Deque's axe for integration and e2e tests on a project that uses oruga (jest-axe for integration, axe via nightwatch for e2e). We recently bumped a few (edit: oruga) versions from 0.5.10 to 0.8.3. The change created several accessibility problems that jest-axe is catching, including:

• incorrect aria in the steps component
• incorrect aria in the switch component
• nested interactive controls in the switch component

Adding axe to the tests for this project in addition to the recommendations above could help prevent future breaking updates.

[mlmoravek]

@mmazanec22 I have no experience with axe. Would you like to make a PR with an example of how to use it?
However, you are always welcome to add some a11y improvements to the codebase :)

[mmazanec22]

@mlmoravek I made an attempt with #846 and fixed an a11y issue in the steps component. If this looks like an ok approach, I'd be happy to continue with the other components that were flagged.

[mlmoravek]

@mmazanec22 Since the axe setup is now merged, you are welcome to add more tests and suggest a11y improvements if you can :)

[jh0ker]

Not sure if this belongs here or in a separate issue, but the Dropdown component can't be controlled using the keyboard.

According to https://www.w3.org/WAI/ARIA/apg/patterns/combobox/examples/combobox-select-only/ users should be able to use the arrow keys to highlight items and scroll through the list, and select items using Enter or the spacebar. I believe this would require tracking the currently highlighted item using state.

A quick and "dirty" but simple solution could be to register a @keypress handler on the dropdown item like this:

function onKeyPress(event: KeyboardEvent): void {
    if (!isClickable.value) return;
    if (event.key === "Enter" || event.key === " ") {
        event.preventDefault();
        parent.value.selectItem(itemValue as T);
        emits("click", itemValue as T, event);
    }
}

This would at least allow using the dropdown using keyboard only, since it is currently possible to tab through the items (not following spec either, but well).

[mlmoravek]

@jh0ker You are always welcome to make such a11y suggestions. And I think a new issue for each is better. :)