Initial work is done

node_modules/undici/lib/compat/dispatcher-weakref.js

@@ -0,0 +1,38 @@
+'use strict'
+
+/* istanbul ignore file: only for Node 12 */
+
+const { kConnected, kSize } = require('../core/symbols')
+
+class CompatWeakRef {
+  constructor (value) {
+    this.value = value
+  }
+
+  deref () {
+    return this.value[kConnected] === 0 && this.value[kSize] === 0
+      ? undefined
+      : this.value
+  }
+}
+
+class CompatFinalizer {
+  constructor (finalizer) {
+    this.finalizer = finalizer
+  }
+
+  register (dispatcher, key) {
+    dispatcher.on('disconnect', () => {
+      if (dispatcher[kConnected] === 0 && dispatcher[kSize] === 0) {
+        this.finalizer(key)
+      }
+    })
+  }
+}
+
+module.exports = function () {
+  return {
+    WeakRef: global.WeakRef || CompatWeakRef,
+    FinalizationRegistry: global.FinalizationRegistry || CompatFinalizer
+  }
+}