get-non-interactive-element-role-schemas.ts

import type {
  ARIARoleDefinitionKey,
  ARIARoleRelationConcept,
} from 'aria-query';
import { elementRoles, roles } from 'aria-query';

let nonInteractiveElementRoleSchemas: ARIARoleRelationConcept[] | null = null;
let nonInteractiveRoles: Set<ARIARoleDefinitionKey> | null = null;

// These functions follow the lazy initialization pattern.
// Since this is a top-level module (it will be included via `require`),
// we do not need to initialize the `nonInteractiveElementRoleSchemas` or
// `nonInteractiveRoles` until the functions are called for the first time,
// so we will not take up the memory.
export function getNonInteractiveElementRoleSchemas(): ARIARoleRelationConcept[] {
  if (nonInteractiveElementRoleSchemas === null) {
    const elementRoleEntries = [...elementRoles.entries()];

    nonInteractiveElementRoleSchemas = elementRoleEntries.reduce<
      ARIARoleRelationConcept[]
    >((accumulator, [elementSchema, roleSet]) => {
      return accumulator.concat(
        [...roleSet].every((role) => getNonInteractiveRoles().has(role))
          ? elementSchema
          : [],
      );
    }, []);
  }

  return nonInteractiveElementRoleSchemas;
}

export function getNonInteractiveRoles(): Set<ARIARoleDefinitionKey> {
  if (nonInteractiveRoles === null) {
    const roleKeys = [...roles.keys()];
    nonInteractiveRoles = new Set<ARIARoleDefinitionKey>(
      roleKeys
        .filter((name) => {
          const role = roles.get(name);
          return (
            role &&
            !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',
        ),
    );
  }

  return nonInteractiveRoles;
}