lib: support BigInt in querystring.stringify

Fixes: https://github.com/nodejs/node/issues/36080

PR-URL: https://github.com/nodejs/node/pull/36499
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

doc/api/querystring.md

@@ -122,8 +122,9 @@ The `querystring.stringify()` method produces a URL query string from a
 given `obj` by iterating through the object's "own properties".
 
 It serializes the following types of values passed in `obj`:
-{string|number|boolean|string[]|number[]|boolean[]}
-Any other input values will be coerced to empty strings.
+{string|number|bigint|boolean|string[]|number[]|bigint[]|boolean[]}
+The numeric values must be finite. Any other input values will be coerced to
+empty strings.
 
 ```js
 querystring.stringify({ foo: 'bar', baz: ['qux', 'quux'], corge: '' });

lib/querystring.js

@@ -162,6 +162,8 @@ function stringifyPrimitive(v) {
     return v;
   if (typeof v === 'number' && NumberIsFinite(v))
     return '' + v;
+  if (typeof v === 'bigint')
+    return '' + v;
   if (typeof v === 'boolean')
     return v ? 'true' : 'false';
   return '';
@@ -176,6 +178,8 @@ function encodeStringified(v, encode) {
     // escaping due to the inclusion of a '+' in the output
     return (MathAbs(v) < 1e21 ? '' + v : encode('' + v));
   }
+  if (typeof v === 'bigint')
+    return '' + v;
   if (typeof v === 'boolean')
     return v ? 'true' : 'false';
   return '';

test/parallel/test-querystring.js

@@ -273,6 +273,24 @@ qsWeirdObjects.forEach((testCase) => {
   assert.strictEqual(qs.stringify(testCase[0]), testCase[1]);
 });
 
+// BigInt values
+
+assert.strictEqual(qs.stringify({ foo: 2n ** 1023n }),
+                   'foo=' + 2n ** 1023n);
+assert.strictEqual(qs.stringify([0n, 1n, 2n]),
+                   '0=0&1=1&2=2');
+
+assert.strictEqual(qs.stringify({ foo: 2n ** 1023n },
+                                null,
+                                null,
+                                { encodeURIComponent: (c) => c }),
+                   'foo=' + 2n ** 1023n);
+assert.strictEqual(qs.stringify([0n, 1n, 2n],
+                                null,
+                                null,
+                                { encodeURIComponent: (c) => c }),
+                   '0=0&1=1&2=2');
+
 // Invalid surrogate pair throws URIError
 assert.throws(
   () => qs.stringify({ foo: '\udc00' }),