onDestroy for ssr

Author: dummdidumm

packages/svelte/src/internal/server/index.js

@@ -79,6 +79,12 @@ export function assign_payload(p1, p2) {
 	p1.anchor = p2.anchor;
 }
 
+/**
+ * Array of `onDestroy` callbacks that should be called at the end of the server render function
+ * @type {Function[]}
+ */
+export let on_destroy = [];
+
 /**
  * @param {(...args: any[]) => void} component
  * @param {{ props: Record<string, any>; context?: Map<any, any> }} options
@@ -90,6 +96,8 @@ export function render(component, options) {
 	const root_head_anchor = create_anchor(payload.head);
 
 	set_is_ssr(true);
+	const prev_on_destroy = on_destroy;
+	on_destroy = [];
 	payload.out += root_anchor;
 
 	if (options.context) {
@@ -102,6 +110,8 @@ export function render(component, options) {
 		$.pop();
 	}
 	payload.out += root_anchor;
+	for (const cleanup of on_destroy) cleanup();
+	on_destroy = prev_on_destroy;
 	set_is_ssr(false);
 
 	return {

packages/svelte/src/main/main-server.js

@@ -1,3 +1,5 @@
+import { on_destroy } from '../internal/server/index.js';
+
 export {
 	createRoot,
 	createEventDispatcher,
@@ -6,7 +8,6 @@ export {
 	getContext,
 	hasContext,
 	mount,
-	onDestroy,
 	setContext,
 	tick,
 	untrack
@@ -15,6 +16,11 @@ export {
 /** @returns {void} */
 export function onMount() {}
 
+/** @param {Function} fn */
+export function onDestroy(fn) {
+	on_destroy.push(fn);
+}
+
 /** @returns {void} */
 export function beforeUpdate() {}