Implement interactive-supports-focus

src/compiler/compile/compiler_warnings.ts

@@ -166,6 +166,10 @@ export default {
 		code: 'a11y-img-redundant-alt',
 		message: 'A11y: Screenreaders already announce <img> elements as an image.'
 	},
+	a11y_interactive_supports_focus: (role: string) => ({
+		code: 'a11y-no-noninteractive-element-interactions',
+		message: `A11y: Elements with the '${role}' interactive role must have a tabindex value.`
+	}),
 	a11y_label_has_associated_control: {
 		code: 'a11y-label-has-associated-control',
 		message: 'A11y: A form label must be associated with a control.'

src/compiler/compile/nodes/Element.ts

@@ -25,7 +25,7 @@ import { Literal } from 'estree';
 import compiler_warnings from '../compiler_warnings';
 import compiler_errors from '../compiler_errors';
 import { ARIARoleDefinitionKey, roles, aria, ARIAPropertyDefinition, ARIAProperty } from 'aria-query';
-import { is_interactive_element, is_non_interactive_element, is_non_interactive_roles, is_presentation_role, is_interactive_roles, is_hidden_from_screen_reader, is_semantic_role_element, is_abstract_role } from '../utils/a11y';
+import { is_interactive_element, is_non_interactive_element, is_non_interactive_roles, is_presentation_role, is_interactive_roles, is_hidden_from_screen_reader, is_semantic_role_element, is_abstract_role, is_static_element, has_disabled_attribute } from '../utils/a11y';
 
 const aria_attributes = 'activedescendant atomic autocomplete busy checked colcount colindex colspan controls current describedby description details disabled dropeffect errormessage expanded flowto grabbed haspopup hidden invalid keyshortcuts label labelledby level live modal multiline multiselectable orientation owns placeholder posinset pressed readonly relevant required roledescription rowcount rowindex rowspan selected setsize sort valuemax valuemin valuenow valuetext'.split(' ');
 const aria_attribute_set = new Set(aria_attributes);
@@ -75,6 +75,15 @@ const a11y_labelable = new Set([
 	'textarea'
 ]);
 
+const a11y_interactive_handlers = new Set([
+	'click',
+	'mousedown',
+	'mouseup',
+	'keypress',
+	'keydown',
+	'keyup'
+]);
+
 const a11y_nested_implicit_semantics = new Map([
 	['header', 'banner'],
 	['footer', 'contentinfo']
@@ -603,6 +612,21 @@ export default class Element extends Node {
 							}
 						}
 
+						// interactive-supports-focus
+						if (
+							!has_disabled_attribute(attribute_map) &&
+							!is_hidden_from_screen_reader(this.name, attribute_map) &&
+							!is_presentation_role(current_role) &&
+							is_interactive_roles(current_role) &&
+							is_static_element(this.name, attribute_map) &&
+							!attribute_map.get('tabindex')
+						) {
+							const has_interactive_handlers = handlers.some((handler) => a11y_interactive_handlers.has(handler.name));
+							if (has_interactive_handlers) {
+								component.warn(this, compiler_warnings.a11y_interactive_supports_focus(current_role));
+							}
+						}
+
 						// no-interactive-element-to-noninteractive-role
 						if (is_interactive_element(this.name, attribute_map) && (is_non_interactive_roles(current_role) || is_presentation_role(current_role))) {
 							component.warn(this, compiler_warnings.a11y_no_interactive_element_to_noninteractive_role(current_role, this.name));

src/compiler/compile/utils/a11y.ts

@@ -68,6 +68,24 @@ export function is_hidden_from_screen_reader(tag_name: string, attribute_map: Ma
 	return aria_hidden_value === true || aria_hidden_value === 'true';
 }
 
+export function has_disabled_attribute(attribute_map: Map<string, Attribute>) {
+	const disabled_attr = attribute_map.get('disabled');
+	const disabled_attr_value = disabled_attr && disabled_attr.get_static_value();
+	if (disabled_attr_value) {
+		return true;
+	}
+
+	const aria_disabled_attr = attribute_map.get('aria-disabled');
+	if (aria_disabled_attr) {
+		const aria_disabled_attr_value = aria_disabled_attr.get_static_value();
+		if (aria_disabled_attr_value === true) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
 const non_interactive_element_role_schemas: ARIARoleRelationConcept[] = [];
 
 elementRoles.entries().forEach(([schema, roles]) => {