Merge branch 'version-4' into legacy-packages

Author: benmccann

.github/workflows/ci.yml

@@ -11,8 +11,17 @@ jobs:
     timeout-minutes: 15
     strategy:
       matrix:
-        node-version: [14, 16, 18]
-        os: [ubuntu-latest, windows-latest, macOS-latest]
+        include:
+          - node-version: 14
+            os: ubuntu-latest
+          - node-version: 14
+            os: windows-latest
+          - node-version: 14
+            os: macOS-latest
+          - node-version: 16
+            os: ubuntu-latest
+          - node-version: 18
+            os: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3
@@ -37,7 +46,17 @@ jobs:
     timeout-minutes: 10
     strategy:
       matrix:
-        os: [ubuntu-latest, windows-latest, macOS-latest]
+        include:
+          - node-version: 14
+            os: ubuntu-latest
+          - node-version: 14
+            os: windows-latest
+          - node-version: 14
+            os: macOS-latest
+          - node-version: 16
+            os: ubuntu-latest
+          - node-version: 18
+            os: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3

CHANGELOG.md

@@ -2,8 +2,14 @@
 
 ## Unreleased (4.0)
 
-* Minimum supported Node version is now Node 14
-* Minimum supported webpack version is now webpack 5
+* **breaking** Minimum supported Node version is now Node 14
+* **breaking** Minimum supported webpack version is now webpack 5
+* **breaking** Minimum supported TypeScript version is now TypeScript 5 (it will likely work with lower versions, but we make no guarantees about that)
+* **breaking** Stricter types for `createEventDispatcher` (see PR for migration instructions) ([#7224](https://github.com/sveltejs/svelte/pull/7224))
+* **breaking** Stricter types for `Action` and `ActionReturn` (see PR for migration instructions) ([#7224](https://github.com/sveltejs/svelte/pull/7224))
+* Add `a11y no-noninteractive-element-interactions` rule ([#8391](https://github.com/sveltejs/svelte/pull/8391))
+* Add `a11y-no-static-element-interactions`rule ([#8251](https://github.com/sveltejs/svelte/pull/8251))
+* Bind `null` option and input values consistently ([#8312](https://github.com/sveltejs/svelte/issues/8312))
 
 ## Unreleased (3.0)
 

package.json

@@ -90,7 +90,7 @@
   },
   "types": "types/runtime/index.d.ts",
   "scripts": {
-    "test": "npm run test:unit && npm run test:integration",
+    "test": "npm run test:unit && npm run test:integration && echo \"manually check that there are no type errors in test/types by opening the files in there\"",
     "test:integration": "mocha --exit",
     "test:unit": "mocha --config .mocharc.unit.js --exit",
     "quicktest": "mocha --exit",

site/content/docs/06-accessibility-warnings.md

@@ -288,6 +288,20 @@ Some HTML elements have default ARIA roles. Giving these elements an ARIA role t
 
 ---
 
+### `a11y-no-noninteractive-element-interactions`
+
+A non-interactive element does not support event handlers (mouse and key handlers). Non-interactive elements include `<main>`, `<area>`, `<h1>` (,`<h2>`, etc), `<p>`, `<img>`, `<li>`, `<ul>` and `<ol>`. Non-interactive [WAI-ARIA roles](https://www.w3.org/TR/wai-aria-1.1/#usage_intro) include `article`, `banner`, `complementary`, `img`, `listitem`, `main`, `region` and `tooltip`.
+
+```sv
+<!-- `A11y: Non-interactive element <li> should not be assigned mouse or keyboard event listeners.` -->
+<li on:click={() => {}} />
+
+<!-- `A11y: Non-interactive element <div> should not be assigned mouse or keyboard event listeners.` -->
+<div role="listitem" on:click={() => {}} />
+```
+
+---
+
 ### `a11y-no-noninteractive-element-to-interactive-role`
 
 [WAI-ARIA](https://www.w3.org/TR/wai-aria-1.1/#usage_intro) roles should not be used to convert a non-interactive element to an interactive element. Interactive ARIA roles include `button`, `link`, `checkbox`, `menuitem`, `menuitemcheckbox`, `menuitemradio`, `option`, `radio`, `searchbox`, `switch` and `textbox`.

src/compiler/compile/compiler_warnings.ts

@@ -115,10 +115,18 @@ export default {
 		code: 'a11y-no-redundant-roles',
 		message: `A11y: Redundant role '${role}'`
 	}),
+	a11y_no_static_element_interactions: (element: string, handlers: string[]) => ({
+		code: 'a11y-no-static-element-interactions',
+		message: `A11y: <${element}> with ${handlers.join(', ')} ${handlers.length === 1 ? 'handler' : 'handlers'} must have an ARIA role`
+	}),
 	a11y_no_interactive_element_to_noninteractive_role: (role: string | boolean, element: string) => ({
 		code: 'a11y-no-interactive-element-to-noninteractive-role',
 		message: `A11y: <${element}> cannot have role '${role}'`
 	}),
+	a11y_no_noninteractive_element_interactions: (element: string) => ({
+		code: 'a11y-no-noninteractive-element-interactions',
+		message: `A11y: Non-interactive element <${element}> should not be assigned mouse or keyboard event listeners.`
+	}),
 	a11y_no_noninteractive_element_to_interactive_role: (role: string | boolean, element: string) => ({
 		code: 'a11y-no-noninteractive-element-to-interactive-role',
 		message: `A11y: Non-interactive element <${element}> cannot have interactive role '${role}'`

src/compiler/compile/nodes/Element.ts

@@ -11,7 +11,7 @@ import StyleDirective from './StyleDirective';
 import Text from './Text';
 import { namespaces } from '../../utils/namespaces';
 import map_children from './shared/map_children';
-import { is_name_contenteditable, get_contenteditable_attr } from '../utils/contenteditable';
+import { is_name_contenteditable, get_contenteditable_attr, has_contenteditable_attr } from '../utils/contenteditable';
 import { regex_dimensions, regex_starts_with_newline, regex_non_whitespace_character, regex_box_size } from '../../utils/patterns';
 import fuzzymatch from '../../utils/fuzzymatch';
 import list from '../../utils/list';
@@ -102,6 +102,15 @@ const a11y_interactive_handlers = new Set([
 	'mouseup'
 ]);
 
+const a11y_recommended_interactive_handlers = new Set([
+	'click',
+	'mousedown',
+	'mouseup',
+	'keypress',
+	'keydown',
+	'keyup'
+]);
+
 const a11y_nested_implicit_semantics = new Map([
 	['header', 'banner'],
 	['footer', 'contentinfo']
@@ -738,17 +747,19 @@ export default class Element extends Node {
 			}
 		}
 
+		const role = attribute_map.get('role');
+		const role_static_value = role?.get_static_value() as ARIARoleDefinitionKey;
+		const role_value = (role ? role_static_value : get_implicit_role(this.name, attribute_map)) as ARIARoleDefinitionKey;
+
 		// no-noninteractive-tabindex
-		if (!this.is_dynamic_element && !is_interactive_element(this.name, attribute_map) && !is_interactive_roles(attribute_map.get('role')?.get_static_value() as ARIARoleDefinitionKey)) {
+		if (!this.is_dynamic_element && !is_interactive_element(this.name, attribute_map) && !is_interactive_roles(role_static_value)) {
 			const tab_index = attribute_map.get('tabindex');
 			if (tab_index && (!tab_index.is_static || Number(tab_index.get_static_value()) >= 0)) {
 				component.warn(this, compiler_warnings.a11y_no_noninteractive_tabindex);
 			}
 		}
 
 		// role-supports-aria-props
-		const role = attribute_map.get('role');
-		const role_value = (role ? role.get_static_value() : get_implicit_role(this.name, attribute_map)) as ARIARoleDefinitionKey;
 		if (typeof role_value === 'string' && roles.has(role_value)) {
 			const { props } = roles.get(role_value);
 			const invalid_aria_props = new Set(aria.keys().filter(attribute => !(attribute in props)));
@@ -762,6 +773,45 @@ export default class Element extends Node {
 					}
 				});
 		}
+
+		// no-noninteractive-element-interactions
+		if (
+			!has_contenteditable_attr(this) &&
+			!is_hidden_from_screen_reader(this.name, attribute_map) &&
+			!is_presentation_role(role_static_value) &&
+			((!is_interactive_element(this.name, attribute_map) && 
+				is_non_interactive_roles(role_static_value)) ||
+			 (is_non_interactive_element(this.name, attribute_map) && !role))
+		) {
+			const has_interactive_handlers = handlers.some((handler) => a11y_recommended_interactive_handlers.has(handler.name));
+			if (has_interactive_handlers) {
+				component.warn(this, compiler_warnings.a11y_no_noninteractive_element_interactions(this.name));
+			}
+		}
+
+		const has_dynamic_role = attribute_map.get('role') && !attribute_map.get('role').is_static;
+
+		// no-static-element-interactions
+		if (
+			!has_dynamic_role &&
+			!is_hidden_from_screen_reader(this.name, attribute_map) &&
+			!is_presentation_role(role_static_value) &&
+			!is_interactive_element(this.name, attribute_map) &&
+			!is_interactive_roles(role_static_value) &&
+			!is_non_interactive_element(this.name, attribute_map) &&
+			!is_non_interactive_roles(role_static_value) &&
+			!is_abstract_role(role_static_value)
+		) {
+			const interactive_handlers = handlers
+				.map((handler) => handler.name)
+				.filter((handlerName) => a11y_interactive_handlers.has(handlerName));
+			if (interactive_handlers.length > 0) {
+				component.warn(
+					this,
+					compiler_warnings.a11y_no_static_element_interactions(this.name, interactive_handlers)
+				);
+			}
+		}
 	}
 
 	validate_special_cases() {

src/compiler/compile/render_dom/wrappers/Element/Attribute.ts

@@ -172,7 +172,7 @@ export default class AttributeWrapper extends BaseAttributeWrapper {
 		}
 
 		if (is_indirectly_bound_value) {
-			const update_value = b`${element.var}.value = ${element.var}.__value;`;
+			const update_value = b`@set_input_value(${element.var}, ${element.var}.__value);`;
 			block.chunks.hydrate.push(update_value);
 
 			updater = b`

src/compiler/compile/utils/a11y.ts

@@ -19,7 +19,8 @@ const non_interactive_roles = new Set(
 				// 'toolbar' does not descend from widget, but it does support
 				// aria-activedescendant, thus in practice we treat it as a widget.
 				// focusable tabpanel elements are recommended if any panels in a set contain content where the first element in the panel is not focusable.
-				!['toolbar', 'tabpanel'].includes(name) &&
+				// 'generic' is meant to have no semantic meaning.
+				!['toolbar', 'tabpanel', 'generic'].includes(name) &&
 				!role.superClass.some((classes) => classes.includes('widget'))
 			);
 		})
@@ -31,7 +32,11 @@ const non_interactive_roles = new Set(
 );
 
 const interactive_roles = new Set(
-	non_abstract_roles.filter((name) => !non_interactive_roles.has(name))
+	non_abstract_roles.filter((name) => 
+		!non_interactive_roles.has(name) &&
+		// 'generic' is meant to have no semantic meaning.
+		name !== 'generic'
+	)
 );
 
 export function is_non_interactive_roles(role: ARIARoleDefinitionKey) {

src/runtime/action/index.ts

@@ -1,7 +1,8 @@
 /**
  * Actions can return an object containing the two properties defined in this interface. Both are optional.
  * - update: An action can have a parameter. This method will be called whenever that parameter changes,
- *   immediately after Svelte has applied updates to the markup.
+ *   immediately after Svelte has applied updates to the markup. `ActionReturn` and `ActionReturn<never>` both
+ *   mean that the action accepts no parameters, which makes it illegal to set the `update` method.
  * - destroy: Method that is called after the element is unmounted
  *
  * Additionally, you can specify which additional attributes and events the action enables on the applied element.
@@ -25,8 +26,8 @@
  *
  * Docs: https://svelte.dev/docs#template-syntax-element-directives-use-action
  */
-export interface ActionReturn<Parameter = any, Attributes extends Record<string, any> = Record<never, any>> {
-	update?: (parameter: Parameter) => void;
+export interface ActionReturn<Parameter = never, Attributes extends Record<string, any> = Record<never, any>> {
+	update?: [Parameter] extends [never] ? never : (parameter: Parameter) => void;
 	destroy?: () => void;
 	/**
 	 * ### DO NOT USE THIS
@@ -42,15 +43,21 @@ export interface ActionReturn<Parameter = any, Attributes extends Record<string,
  * The following example defines an action that only works on `<div>` elements
  * and optionally accepts a parameter which it has a default value for:
  * ```ts
- * export const myAction: Action<HTMLDivElement, { someProperty: boolean }> = (node, param = { someProperty: true }) => {
+ * export const myAction: Action<HTMLDivElement, { someProperty: boolean } | undefined> = (node, param = { someProperty: true }) => {
  *   // ...
  * }
  * ```
+ * `Action<HTMLDivElement>` and `Action<HTMLDiveElement, never>` both signal that the action accepts no parameters.
+ *
  * You can return an object with methods `update` and `destroy` from the function and type which additional attributes and events it has.
  * See interface `ActionReturn` for more details.
  *
  * Docs: https://svelte.dev/docs#template-syntax-element-directives-use-action
  */
-export interface Action<Element = HTMLElement, Parameter = any, Attributes extends Record<string, any> = Record<never, any>> {
-	<Node extends Element>(node: Node, parameter?: Parameter): void | ActionReturn<Parameter, Attributes>;
+export interface Action<Element = HTMLElement, Parameter = never, Attributes extends Record<string, any> = Record<never, any>> {
+	<Node extends Element>(...args: [Parameter] extends [never] ? [node: Node] : undefined extends Parameter ? [node: Node, parameter?: Parameter] : [node: Node, parameter: Parameter]): void | ActionReturn<Parameter, Attributes>;
 }
+
+// Implementation notes:
+// - undefined extends X instead of X extends undefined makes this work better with both strict and nonstrict mode
+// - [X] extends [never] is needed, X extends never would reduce the whole resulting type to never and not to one of the condition outcomes

src/runtime/internal/lifecycle.ts

@@ -56,6 +56,17 @@ export function onDestroy(fn: () => any) {
 	get_current_component().$$.on_destroy.push(fn);
 }
 
+export interface EventDispatcher<EventMap extends Record<string, any>> {
+	// Implementation notes:
+	// - undefined extends X instead of X extends undefined makes this work better with both strict and nonstrict mode
+	// - [X] extends [never] is needed, X extends never would reduce the whole resulting type to never and not to one of the condition outcomes
+	<Type extends keyof EventMap>(
+		...args: [EventMap[Type]] extends [never] ? [type: Type, parameter?: null | undefined, options?: DispatchOptions] :
+		null extends EventMap[Type] ? [type: Type, parameter?: EventMap[Type], options?: DispatchOptions] :
+		undefined extends EventMap[Type] ? [type: Type, parameter?: EventMap[Type], options?: DispatchOptions] :
+		[type: Type, parameter: EventMap[Type], options?: DispatchOptions]): boolean;
+}
+
 export interface DispatchOptions {
 	cancelable?: boolean;
 }
@@ -68,20 +79,23 @@ export interface DispatchOptions {
  * [CustomEvent](https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent). 
  * These events do not [bubble](https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Building_blocks/Events#Event_bubbling_and_capture).
  * The `detail` argument corresponds to the [CustomEvent.detail](https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent/detail) 
- * property and can contain any type of data. 
+ * property and can contain any type of data.
+ * 
+ * The event dispatcher can be typed to narrow the allowed event names and the type of the `detail` argument:
+ * ```ts
+ * const dispatch = createEventDispatcher<{
+ *  loaded: never; // does not take a detail argument
+ *  change: string; // takes a detail argument of type string, which is required
+ *  optional: number | null; // takes an optional detail argument of type number
+ * }>();
+ * ```
  * 
  * https://svelte.dev/docs#run-time-svelte-createeventdispatcher
  */
-export function createEventDispatcher<EventMap extends {} = any>(): <
-	EventKey extends Extract<keyof EventMap, string>
->(
-	type: EventKey,
-	detail?: EventMap[EventKey],
-	options?: DispatchOptions
-) => boolean {
+export function createEventDispatcher<EventMap extends Record<string, any> = any>(): EventDispatcher<EventMap> {
 	const component = get_current_component();
 
-	return (type: string, detail?: any, { cancelable = false } = {}): boolean => {
+	return ((type: string, detail?: any, { cancelable = false } = {}): boolean => {
 		const callbacks = component.$$.callbacks[type];
 
 		if (callbacks) {
@@ -95,7 +109,7 @@ export function createEventDispatcher<EventMap extends {} = any>(): <
 		}
 
 		return true;
-	};
+	}) as EventDispatcher<EventMap>;
 }
 
 /**