eslint-plugin-lit-a11y/lib/utils/isInteractiveElement.js

linting plugin for lit-a11y

const { dom, elementRoles, roles } = require('aria-query');
const { AXObjects, elementAXObjects } = require('@thepassle/axobject-query');

const { attributesComparator } = require('./attributesComparator.js');

const domKeys = [...dom.keys()];
const roleKeys = [...roles.keys()];
const elementRoleEntries = [...elementRoles];

const nonInteractiveRoles = new Set(
  roleKeys
    .filter(name => {
      const role = roles.get(name);
      return (
        !role.abstract &&
        // 'toolbar' does not descend from widget, but it does support
        // aria-activedescendant, thus in practice we treat it as a widget.
        name !== 'toolbar' &&
        !role.superClass.some(classes => classes.includes('widget'))
      );
    })
    .concat(
      // The `progressbar` is descended from `widget`, but in practice, its
      // value is always `readonly`, so we treat it as a non-interactive role.
      'progressbar',
    ),
);

const interactiveRoles = new Set(
  roleKeys
    .filter(name => {
      const role = roles.get(name);
      return (
        !role.abstract &&
        // The `progressbar` is descended from `widget`, but in practice, its
        // value is always `readonly`, so we treat it as a non-interactive role.
        name !== 'progressbar' &&
        role.superClass.some(classes => classes.includes('widget'))
      );
    })
    .concat(
      // 'toolbar' does not descend from widget, but it does support
      // aria-activedescendant, thus in practice we treat it as a widget.
      'toolbar',
    ),
);

const nonInteractiveElementRoleSchemas = elementRoleEntries.reduce(
  (accumulator, [elementSchema, roleSet]) => {
    if ([...roleSet].every(role => nonInteractiveRoles.has(role))) {
      accumulator.push(elementSchema);
    }
    return accumulator;
  },
  [],
);

const interactiveElementRoleSchemas = elementRoleEntries.reduce(
  (accumulator, [elementSchema, roleSet]) => {
    if ([...roleSet].some(role => interactiveRoles.has(role))) {
      accumulator.push(elementSchema);
    }
    return accumulator;
  },
  [],
);

const interactiveAXObjects = new Set(
  [...AXObjects.keys()].filter(name => AXObjects.get(name).type === 'widget'),
);

const interactiveElementAXObjectSchemas = [...elementAXObjects].reduce(
  (accumulator, [elementSchema, AXObjectSet]) => {
    if ([...AXObjectSet].every(role => interactiveAXObjects.has(role))) {
      accumulator.push(elementSchema);
    }
    return accumulator;
  },
  [],
);

function checkIsInteractiveElement(tagName, attributes) {
  function elementSchemaMatcher(elementSchema) {
    return (
      tagName === elementSchema.name && attributesComparator(elementSchema.attributes, attributes)
    );
  }
  // Check in elementRoles for inherent interactive role associations for
  // this element.
  const isInherentInteractiveElement = interactiveElementRoleSchemas.some(elementSchemaMatcher);
  if (isInherentInteractiveElement) {
    return true;
  }
  // Check in elementRoles for inherent non-interactive role associations for
  // this element.
  const isInherentNonInteractiveElement =
    nonInteractiveElementRoleSchemas.some(elementSchemaMatcher);
  if (isInherentNonInteractiveElement) {
    return false;
  }
  // Check in elementAXObjects for AX Tree associations for this element.
  const isInteractiveAXElement = interactiveElementAXObjectSchemas.some(elementSchemaMatcher);
  if (isInteractiveAXElement) {
    return true;
  }

  return false;
}

/**
 * Returns boolean indicating whether the given element is
 * interactive on the DOM or not. Usually used when an element
 * has a dynamic handler on it and we need to discern whether or not
 * it's intention is to be interacted with on the DOM.
 * @param {import('parse5-htmlparser2-tree-adapter').Element} element
 */
const isInteractiveElement = element => {
  if (!domKeys.includes(element.name)) {
    return false;
  }

  return checkIsInteractiveElement(element.name, element.attribs);
};

module.exports = {
  isInteractiveElement,
};