add Attachment interface

Author: Rich-Harris

documentation/docs/03-template-syntax/[email protected]

@@ -9,8 +9,9 @@ Attachments are functions that run when an element is mounted to the DOM. Option
 
 ```svelte
 <script>
-	function myAttachment(node) {
-		console.log(node.nodeName); // 'DIV'
+	/** @type {import('svelte/attachments').Attachment} */
+	function myAttachment(element) {
+		console.log(element.nodeName); // 'DIV'
 
 		return () => {
 			console.log('cleaning up');
@@ -33,9 +34,13 @@ A useful pattern is for a function, such as `tooltip` in this example, to _retur
 
 	let content = $state('Hello!');
 
+	/**
+	 * @param {string} content
+	 * @returns {import('svelte/attachments').Attachment}
+	 */
 	function tooltip(content) {
-		return (node) => {
-			const tooltip = tippy(node, { content });
+		return (element) => {
+			const tooltip = tippy(element, { content });
 			return tooltip.destroy;
 		};
 	}
@@ -106,9 +111,13 @@ This allows you to create _wrapper components_ that augment elements ([demo](/pl
 
 	let content = $state('Hello!');
 
+	/**
+	 * @param {string} content
+	 * @returns {import('svelte/attachments').Attachment}
+	 */
 	function tooltip(content) {
-		return (node) => {
-			const tooltip = tippy(node, { content });
+		return (element) => {
+			const tooltip = tippy(element, { content });
 			return tooltip.destroy;
 		};
 	}

packages/svelte/scripts/generate-types.js

@@ -35,7 +35,7 @@ await createBundle({
 		[pkg.name]: `${dir}/src/index.d.ts`,
 		[`${pkg.name}/action`]: `${dir}/src/action/public.d.ts`,
 		[`${pkg.name}/animate`]: `${dir}/src/animate/public.d.ts`,
-		[`${pkg.name}/attachments`]: `${dir}/src/attachments/index.js`,
+		[`${pkg.name}/attachments`]: `${dir}/src/attachments/public.d.ts`,
 		[`${pkg.name}/compiler`]: `${dir}/src/compiler/public.d.ts`,
 		[`${pkg.name}/easing`]: `${dir}/src/easing/index.js`,
 		[`${pkg.name}/legacy`]: `${dir}/src/legacy/legacy-client.js`,

packages/svelte/src/attachments/public.d.ts

@@ -0,0 +1,5 @@
+export interface Attachment {
+	(element: Element): void | (() => void);
+}
+
+export * from './index.js';

packages/svelte/types/index.d.ts

@@ -625,6 +625,9 @@ declare module 'svelte/animate' {
 }
 
 declare module 'svelte/attachments' {
+	export interface Attachment {
+		(element: Element): void | (() => void);
+	}
 	/**
 	 * Creates an object key that will be recognised as an attachment when the object is spread onto an element,
 	 * as a programmatic alternative to using `{@attach ...}`. This can be useful for library authors, though