Add JS::Undefined and JS::Null

just for convenience

Author: mame

ext/js/lib/js.rb

@@ -13,6 +13,8 @@
 #   end
 #
 module JS
+  Undefined = JS.eval("return undefined")
+  Null = JS.eval("return null")
 end
 
 class JS::Object

packages/npm-packages/ruby-wasm-wasi/test/js_from_rb.test.ts

@@ -228,4 +228,16 @@ describe("Manipulation of JS from Ruby", () => {
       object.call("itself");
     }
   });
+
+  test.each([
+    { expr: `JS::Undefined`, expected: "undefined" },
+    { expr: `JS::Null`, expected: "null" },
+  ])("constant %s", async ({ expr, expected }) => {
+    const vm = await initRubyVM();
+    const result = vm.eval(`
+      require "js"
+      ${expr}.inspect
+    `);
+    expect(result.toJS()).toEqual(expected);
+  });
 });