url: fix URLSearchParams(null) to prudce null= per spec

marcopiraccini · aduh95 · commit 898c4a81eefb · 2026-06-25T16:07:38.000+02:00
Signed-off-by: marcopiraccini <marco.piraccini@gmail.com> PR-URL: #63782 Fixes: #63559 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: René <contact.9a5d6388@renegade334.me.uk> Reviewed-By: Gürgün Dayıoğlu <hey@gurgun.day> Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com> Reviewed-By: Chemi Atlow <chemi@atlow.co.il> Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
diff --git a/lib/internal/url.js b/lib/internal/url.js
@@ -337,9 +337,9 @@ class URLSearchParams {
   constructor(init = undefined) {
     markTransferMode(this, false, false);
 
-    if (init == null) {
+    if (init === undefined) {
       // Do nothing
-    } else if (typeof init === 'object' || typeof init === 'function') {
+    } else if (init !== null && (typeof init === 'object' || typeof init === 'function')) {
       const method = init[SymbolIterator];
       if (method === this[SymbolIterator] && #searchParams in init) {
         // While the spec does not have this branch, we can use it as a
diff --git a/test/parallel/test-whatwg-url-custom-searchparams-constructor.js b/test/parallel/test-whatwg-url-custom-searchparams-constructor.js
@@ -28,8 +28,14 @@ function makeIterableFunc(array) {
   let params;
   params = new URLSearchParams(undefined);
   assert.strictEqual(params.toString(), '');
+  // Per WebIDL union resolution, null is coerced to the USVString "null".
+  // Refs: https://url.spec.whatwg.org/#interface-urlsearchparams
   params = new URLSearchParams(null);
-  assert.strictEqual(params.toString(), '');
+  assert.strictEqual(params.toString(), 'null=');
+  params = new URLSearchParams(false);
+  assert.strictEqual(params.toString(), 'false=');
+  params = new URLSearchParams(0);
+  assert.strictEqual(params.toString(), '0=');
   params = new URLSearchParams(
     makeIterableFunc([['key', 'val'], ['key2', 'val2']])
   );
