fixed where updating the search wouldn't keep the new order of how they are added

packages/svelte/src/reactivity/url-search-params.js

@@ -2,27 +2,28 @@ import { make_reactive } from './utils.js';
 
 export const ReactiveURLSearchParams = make_reactive(URLSearchParams, {
 	write_properties: ['append', 'delete', 'set', 'sort'],
-	read_properties: ['get', 'has'],
+	read_properties: ['get', 'has', 'getAll'],
 	interceptors: {
 		set: (notify_read_properties, value, property, ...params) => {
 			if (typeof params[0] == 'string' && value.get(params[0]) === params[1]) {
 				return false;
 			}
-			notify_read_properties(['get', 'has'], params[0]);
+			notify_read_properties(['get', 'has', 'getAll'], params[0]);
 			return true;
 		},
 		append: (notify_read_properties, value, property, ...params) => {
-			if (typeof params[0] == 'string' && value.get(params[0]) === params[1]) {
+			notify_read_properties(['getAll'], params[0]);
-				return false;
+
+			if (typeof params[0] == 'string' && !value.has(params[0])) {
+				notify_read_properties(['get', 'has'], params[0]);
 			}
-			notify_read_properties(['get', 'has'], params[0]);
 			return true;
 		},
 		delete: (notify_read_properties, value, property, ...params) => {
 			if (typeof params[0] == 'string' && !value.has(params[0])) {
 				return false;
 			}
-			notify_read_properties(['get', 'has'], params[0]);
+			notify_read_properties(['get', 'has', 'getAll'], params[0]);
 			return true;
 		}
 	}

packages/svelte/src/reactivity/url-search-params.test.ts

@@ -113,3 +113,39 @@ test('URLSearchParams.get', () => {
 
 	cleanup();
 });
+
+test('URLSearchParams.getAll', () => {
+	const params = new ReactiveURLSearchParams('a=b&c=d');
+	const log: any = [];
+
+	const cleanup = effect_root(() => {
+		render_effect(() => {
+			log.push(params.get('a'));
+		});
+		render_effect(() => {
+			log.push(params.get('c'));
+		});
+		render_effect(() => {
+			log.push(params.get('q'));
+		});
+		render_effect(() => {
+			log.push(params.getAll('a'));
+		});
+		render_effect(() => {
+			log.push(params.getAll('q'));
+		});
+	});
+
+	flushSync(() => {
+		// this shouldn't affect params.get(a) because it already exists
+		params.append('a', 'b1');
+	});
+
+	flushSync(() => {
+		params.append('q', 'z');
+	});
+
+	assert.deepEqual(log, ['b', 'd', null, ['b'], [], ['b', 'b1'], 'z', ['z']]);
+
+	cleanup();
+});

packages/svelte/src/reactivity/url.js

@@ -1,3 +1,4 @@
+import { untrack } from '../index-client.js';
 import { ReactiveURLSearchParams } from './url-search-params.js';
 import { make_reactive } from './utils.js';
 
@@ -71,21 +72,44 @@ class URLWithReactiveSearchParams extends URL {
 		}
 
 		if (url_updated) {
-			Array.from(this.searchParams.keys()).forEach((key) => {
+			this.#update_search_params_from_url();
-				// remove keys that don't exist anymore
-				if (!super.searchParams.has(key)) {
-					this.searchParams.delete(key);
-				}
-			});
-			for (const key of super.searchParams.keys()) {
-				// set/update keys
-				this.searchParams.set(key, /** @type {string} */ (super.searchParams.get(key)));
-			}
 		} else if (search_params_updated) {
+			// updating url from params
 			this.search = this.searchParams.toString();
 		}
 	}
 
+	#update_search_params_from_url() {
+		/**
+		 * keeping track of this is required because we have to keep the order in which they are updated
+		 * @type {string[]}
+		 */
+		const keys_with_no_change = [];
+
+		// remove keys that don't exist anymore and notify others
+		for (const [key, value] of Array.from(this.searchParams.entries())) {
+			if (!super.searchParams.has(key) || value == super.searchParams.get(key)) {
+				keys_with_no_change.push(key);
+				untrack(() => {
+					this.searchParams.delete(key);
+				});
+				continue;
+			}
+			this.searchParams.delete(key);
+		}
+
+		// set or update keys based on the params
+		for (const [key, value] of super.searchParams.entries()) {
+			if (keys_with_no_change.includes(key)) {
+				untrack(() => {
+					this.searchParams.set(key, value);
+				});
+				continue;
+			}
+			this.searchParams.set(key, value);
+		}
+	}
+
 	/**
 	 * @override
 	 */

packages/svelte/src/reactivity/url.test.ts

@@ -67,7 +67,6 @@ test('url.searchParams', () => {
 		'foo: baz',
 		'q: true',
 		'search: ?q=kit&foo=baz&foo=qux',
-		'foo: baz',
 		'search: ?q=kit',
 		'foo: null'
 	]);