src: add WeakReference utility

Add a simple `WeakReference` utility that we can use until the
language provides something on its own.

PR-URL: https://github.com/nodejs/node/pull/25993
Fixes: https://github.com/nodejs/node/issues/23862
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Refael Ackermann <refack@gmail.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/test/parallel/test-internal-util-weakreference.js b/test/parallel/test-internal-util-weakreference.js
new file mode 100644
index 0000000000..b48b34fe23
--- /dev/null
+++ b/test/parallel/test-internal-util-weakreference.js
@@ -0,0 +1,17 @@
+// Flags: --expose-internals --expose-gc
+'use strict';
+require('../common');
+const assert = require('assert');
+const { internalBinding } = require('internal/test/binding');
+const { WeakReference } = internalBinding('util');
+
+let obj = { hello: 'world' };
+const ref = new WeakReference(obj);
+assert.strictEqual(ref.get(), obj);
+
+setImmediate(() => {
+  obj = null;
+  global.gc();
+
+  assert.strictEqual(ref.get(), undefined);
+});