Javascript The Good Parts by Douglas Crockford

The good parts of javascript gives you just that, a short language intro, a couple of best practices and unexpectedly some in depth details about why some parts are bad, like big arrays where everything seems to be a string causing slowness, or no scoping of variables so it looks like global rules. Besides that, at the end you get some bad parts as well. Also, also always use !== and === and not their lesser cousins and try to avoid the unary addition operators ++, --. Overall a good little book with lots of information for starters and not only them.