Simon Willison’s Weblog

What are some JavaScript concepts that took you the longest to understand?

30th July 2013

My answer to What are some JavaScript concepts that took you the longest to understand? on Quora

Closures, prototype inheritance, and the “this” keyword.

Once you understand those three, you know most of what there is to know about the JavaScript language in my opinion (with the exception of some of the newer language features like iterators and generators).