a = 1; b = 42; test("basic functionality", () => { expect(delete a).toBeTrue(); expect(() => { a; }).toThrowWithMessage(ReferenceError, "'a' is not defined"); }); test("delete global var after usage", () => { let errors = 0; for (let i = 0; i < 3; ++i) { try { b++; } catch { ++errors; } delete globalThis.b; } expect(errors).toBe(2); });