Add globalThis definition to runtime (#1534)

2 files changed, 11 insertions, 6 deletions

diff --git a/tools/ts_library_builder/build_library.ts b/tools/ts_library_builder/build_library.ts
index 00e942540..0717de987 100644
--- a/tools/ts_library_builder/build_library.ts
+++ b/tools/ts_library_builder/build_library.ts
@@ -156,6 +156,10 @@ export function mergeGlobal({
   // Declare the global variable
   addVariableDeclaration(targetSourceFile, globalVarName, interfaceName, true);
 
+  // `globalThis` accesses the global scope and is defined here:
+  // https://github.com/tc39/proposal-global
+  addVariableDeclaration(targetSourceFile, "globalThis", interfaceName, true);
+
   // Add self reference to the global variable
   addInterfaceProperty(interfaceDeclaration, globalVarName, interfaceName);
 
diff --git a/tools/ts_library_builder/test.ts b/tools/ts_library_builder/test.ts
index b5883433a..ad0d7cfa1 100644
--- a/tools/ts_library_builder/test.ts
+++ b/tools/ts_library_builder/test.ts
@@ -140,24 +140,25 @@ test(function buildLibraryMerge() {
   assertEqual(targetSourceFile.getInterfaces().length, 1);
   const variableDeclarations = targetSourceFile.getVariableDeclarations();
   assertEqual(variableDeclarations[0].getType().getText(), `FooBar`);
-  assertEqual(variableDeclarations[1].getType().getText(), `moduleC.Bar`);
+  assertEqual(variableDeclarations[1].getType().getText(), `FooBar`);
+  assertEqual(variableDeclarations[2].getType().getText(), `moduleC.Bar`);
   assertEqual(
-    variableDeclarations[2].getType().getText(),
+    variableDeclarations[3].getType().getText(),
     `typeof moduleC.qat`
   );
   assertEqual(
-    variableDeclarations[3].getType().getText(),
+    variableDeclarations[4].getType().getText(),
     `typeof moduleE.process`
   );
   assertEqual(
-    variableDeclarations[4].getType().getText(),
+    variableDeclarations[5].getType().getText(),
     `typeof moduleD.reprocess`
   );
   assertEqual(
-    variableDeclarations[5].getType().getText(),
+    variableDeclarations[6].getType().getText(),
     `typeof moduleC.Bar`
   );
-  assertEqual(variableDeclarations.length, 6);
+  assertEqual(variableDeclarations.length, 7);
   const typeAliases = targetSourceFile.getTypeAliases();
   assertEqual(typeAliases[0].getName(), "Bar");
   assertEqual(typeAliases[0].getType().getText(), "moduleC.Bar");