* How to decisively filter competent front end developers in about 3 minutes. Competent people think in terms of graphs that can be walked, accessed, and modified directly. The incompetent ones think in terms of databases in that they can only make queries and expect abstractions and tools to fill their knowledge gap.

* People who write high performance software spend an absurd amount of time measuring things and possibly writing their own tools to provide deeper insights. Other people that talk about performance are hallucinating.

* There are developers that think in terms of other people. Those people put more effort into documentation, content, and architecture. It’s all about what they say. There are developers that think in terms of themselves. They focus on what they believe is easy and stylish. It’s all about what they are willing to do, how to do it, and how it looks.

Everything developers know off the top of their heads come from stuff like those three bullet points and the hours they spend practicing it.