querystring: fix stringify for empty array

PR-URL: #33918
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

Author: sapics

lib/querystring.js

@@ -196,7 +196,6 @@ function stringify(obj, sep, eq, options) {
   if (obj !== null && typeof obj === 'object') {
     const keys = ObjectKeys(obj);
     const len = keys.length;
-    const flast = len - 1;
     let fields = '';
     for (let i = 0; i < len; ++i) {
       const k = keys[i];
@@ -207,20 +206,20 @@ function stringify(obj, sep, eq, options) {
       if (ArrayIsArray(v)) {
         const vlen = v.length;
         if (vlen === 0) continue;
-        const vlast = vlen - 1;
+        if (fields)
+          fields += sep;
         for (let j = 0; j < vlen; ++j) {
+          if (j)
+            fields += sep;
           fields += ks;
           fields += convert(v[j], encode);
-          if (j < vlast)
-            fields += sep;
         }
       } else {
+        if (fields)
+          fields += sep;
         fields += ks;
         fields += convert(v, encode);
       }
-
-      if (i < flast)
-        fields += sep;
     }
     return fields;
   }

test/parallel/test-querystring.js

@@ -144,7 +144,8 @@ const qsWeirdObjects = [
   [{ n: null }, 'n=', { 'n': '' }],
   [{ nan: NaN }, 'nan=', { 'nan': '' }],
   [{ inf: Infinity }, 'inf=', { 'inf': '' }],
-  [{ a: [], b: [] }, '', {}]
+  [{ a: [], b: [] }, '', {}],
+  [{ a: 1, b: [] }, 'a=1', { 'a': '1' }]
 ];
 // }}}