Wow~~ This is really the epitome of JavaScript!! I was so moved by the lecture that I had to write a review right away. If you are preparing for a technical interview, I highly recommend this lecture! It is really helpful because it provides expected problems and solutions. Especially when explaining the ECMA spec, there were many moments when I hit my knee and thought, "Oh, that's what it means..." It wasn't that I didn't know because the spec was in English, but that I only saw what I knew. It was a really thankful lecture because I was able to learn the instructor's deep insight. I listened to it over and over again, and I made a promise to myself to make it perfect! Thank you for the great lecture!