I was reviewing the code spit out by a Yeoman generator, while reading some Angular docs (admittedly out of order), and I has confused about how variables were being defined. I finally read something that explained what to do (add a variable using a specific naming convention to the function declaration). I realized the framework was doing some sort of backhanded meta-programming, and I didn't feel so bad for not understanding what was going on.

The problem with this is you can be a pretty knowledgable JavaScript programmer and still not understand the code or the documentation. For this reason, I've never been a fan of meta-programming in general. Not only do you (as an application programmer) have to understand the language as defined, you have to understand other frameworks' reinterpretation of the language. If you bring in multiple frameworks that do this, it quickly becomes more difficult to reason about what a program does by simply reading the code.