It was really helpful. I attended a 4-month boot camp to become a front-end developer, and studied on my own using materials I found by searching here and there, but it didn't last long. I think it was because I didn't have a clear goal or direction and thought that I could just work hard. The content in the e-book itself was a great help in setting the direction of my future studies, but it was also good that it gave me topics to think deeply about, such as React's useState and useEffect. There is also a sense of pressure that I have to invest more to delve deeper. I'm really glad that I started the new year with such a great lecture...! I hope you continue to update the lectures!