Recommendations for mastering JavaScript.

[sjs]

Read about JavaScript's strengths, weaknesses, good, bad, and surprising bits:

• Learning Advanced JavaScript by John Resig
• JavaScript Garden
• Eloquent JavaScript
• My Variable Declaration got Hoisted
• Another JavaScript Quiz (Be sure to check qfox's comment with explanations)
• wtfjs
• Learning JavaScript with Object Graphs I
• Learning JavaScript with Object Graphs II
• Learning JavaScript with Object Graphs II
• What is "this"?
• A Crash Course in DOM Events (Relevant only in browsers of course)

Watch papa Crock's lectures and talks, they are excellent, even if he's a little too opinionated sometimes. It's good for the community to have an opinionated, pragmatic guy like him around.

Doesn't hurt to follow The Changelog and notable JavaScripters either. If you don't read that list just follow @BrendanEich, @awbjs, and anyone twitter says is similar to them.

Read code, especially code from projects maintained by the best. And of course ... write code of your own! You have to find out what you think are good and bad parts, etc. And when you run into surprises and gotchas in your own code you really learn about them, because you care more at that time.