querystring: simplify stringify method

PR-URL: https://github.com/nodejs/node/pull/26591
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

benchmark/querystring/querystring-stringify.js

@@ -3,8 +3,8 @@ const common = require('../common.js');
 const querystring = require('querystring');
 
 const bench = common.createBenchmark(main, {
-  type: ['noencode', 'encodemany', 'encodelast'],
+  type: ['noencode', 'encodemany', 'encodelast', 'array'],
-  n: [1e7],
+  n: [1e6],
 });
 
 function main({ type, n }) {
@@ -23,6 +23,11 @@ function main({ type, n }) {
       foo: 'bar',
       baz: 'quux',
       xyzzy: 'thu\u00AC'
+    },
+    array: {
+      foo: [],
+      baz: ['bar'],
+      xyzzy: ['bar', 'quux', 'thud']
     }
   };
   const input = inputs[type];

lib/querystring.js

@@ -176,20 +176,20 @@ function stringify(obj, sep, eq, options) {
 
       if (Array.isArray(v)) {
         var vlen = v.length;
+        if (vlen === 0) continue;
         var vlast = vlen - 1;
         for (var j = 0; j < vlen; ++j) {
           fields += ks + encode(stringifyPrimitive(v[j]));
           if (j < vlast)
             fields += sep;
         }
-        if (vlen && i < flast)
-          fields += sep;
       } else {
         fields += ks + encode(stringifyPrimitive(v));
+      }
+
       if (i < flast)
         fields += sep;
     }
-    }
     return fields;
   }
   return '';