In a detailed exploration of dependency injection (DI) for TypeScript, the author shares their journey of developing a custom DI library called Fusion. Frustrated by the complexity of existing DI frameworks, they created a streamlined solution in fewer than 300 lines of code that supports both React and generic TypeScript applications. Fusion leverages TypeScript decorators and JavaScript Proxies to automate the injection of dependencies, focusing on simplicity and flexibility without the need for a traditional container. The library allows for lazy initialization of singletons, enhancing code maintainability and testability while promoting loose coupling between components. Fusion is open-sourced, offering developers the opportunity to explore, customize, and potentially improve upon this lightweight yet effective DI system.