It seems it is not enough to know learn javascript, but then you have factor in the many variations in syntax that result from using the current flavor-of-the-week library.
This list is far from complete and seems to be a small subset when you think about Backbone, underscore, coffescript, xui and more: http://en.wikipedia.org/wiki/Comparison_of_JavaScript_frameworks
I'm not complaining (yet) but it seems that every week there is a new choice, especially now that you have mobile specific ones. I'm concerned that this might be a problem very soon... or do HN readers feel it will eventually consolidate a bit over time?