fix(core): improve global variable detection (#28679)

Closes #16545

PR Close #28679

packages/core/src/util/global.ts

@@ -12,14 +12,23 @@ declare var WorkerGlobalScope: any /** TODO #9100 */;
 // We don't want to include the whole node.d.ts this this compilation unit so we'll just fake
 // the global "global" var for now.
 declare var global: any /** TODO #9100 */;
-const __window = typeof window !== 'undefined' && window;
-const __self = typeof self !== 'undefined' && typeof WorkerGlobalScope !== 'undefined' &&
-    self instanceof WorkerGlobalScope && self;
-const __global = typeof global !== 'undefined' && global;
+// Not yet available in TypeScript: https://github.com/Microsoft/TypeScript/pull/29332
+declare var globalThis: any /** TODO #9100 */;
 
-// Check __global first, because in Node tests both __global and __window may be defined and _global
-// should be __global in that case.
-const _global: {[name: string]: any} = __global || __window || __self;
+function getGlobal(): any {
+  const __globalThis = typeof globalThis !== 'undefined' && globalThis;
+  const __window = typeof window !== 'undefined' && window;
+  const __self = typeof self !== 'undefined' && typeof WorkerGlobalScope !== 'undefined' &&
+      self instanceof WorkerGlobalScope && self;
+  const __global = typeof global !== 'undefined' && global;
+
+  // Always use __globalThis if available, which is the spec-defined global variable across all
+  // environments, then fallback to __global first, because in Node tests both __global and
+  // __window may be defined and _global should be __global in that case.
+  return __globalThis || __global || __window || __self;
+}
+
+const _global = getGlobal();
 
 /**
  * Attention: whenever providing a new value, be sure to add an

packages/core/test/bundling/cyclic_import/bundle.golden_symbols.json

@@ -143,15 +143,9 @@
   {
     "name": "ViewEncapsulation"
   },
-  {
-    "name": "__self"
-  },
   {
     "name": "__values"
   },
-  {
-    "name": "__window"
-  },
   {
     "name": "_currentNamespace"
   },
@@ -329,6 +323,9 @@
   {
     "name": "getElementDepthCount"
   },
+  {
+    "name": "getGlobal"
+  },
   {
     "name": "getHighestElementOrICUContainer"
   },

packages/core/test/bundling/hello_world/bundle.golden_symbols.json

@@ -116,15 +116,9 @@
   {
     "name": "ViewEncapsulation"
   },
-  {
-    "name": "__self"
-  },
   {
     "name": "__values"
   },
-  {
-    "name": "__window"
-  },
   {
     "name": "_global"
   },
@@ -239,6 +233,9 @@
   {
     "name": "getDirectiveDef"
   },
+  {
+    "name": "getGlobal"
+  },
   {
     "name": "getHighestElementOrICUContainer"
   },

packages/core/test/bundling/todo/bundle.golden_symbols.json

@@ -278,18 +278,12 @@
   {
     "name": "__read"
   },
-  {
-    "name": "__self"
-  },
   {
     "name": "__spread"
   },
   {
     "name": "__values"
   },
-  {
-    "name": "__window"
-  },
   {
     "name": "_c0"
   },
@@ -680,6 +674,9 @@
   {
     "name": "getErrorLogger"
   },
+  {
+    "name": "getGlobal"
+  },
   {
     "name": "getHighestElementOrICUContainer"
   },

packages/core/test/util/global_spec.ts

@@ -0,0 +1,25 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {global} from '../../src/util/global';
+
+// Not yet available in TypeScript: https://github.com/Microsoft/TypeScript/pull/29332
+declare var globalThis: any /** TODO #9100 */;
+
+{
+  describe('global', () => {
+    it('should be global this value', () => {
+      const _global = new Function('return this')();
+      expect(global).toBe(_global);
+    });
+
+    if (typeof globalThis !== 'undefined') {
+      it('should use globalThis as global reference', () => { expect(global).toBe(globalThis); });
+    }
+  });
+}