> we still need to target es5 4 years later, This is a dramatic improvement over the 10 year lifespan of IE6 with es3. Once the need to target es5 drops, the

> we still need to target es5 4 years later, This is a dramatic improvement over the 10 year lifespan of IE6 with es3. Once the need to target es5 drops, the next level gets even shorter - I don't think we'll get less than 2 years as a practical matter, but even at a 2 year delay, that's still regularly progress. > a pretty arbitrary subset of the language Best practices don't come from a mathematical model - programming is about communication and being compatible with user/business demands (which keep changing). Thus, best practices come about from a lot of experimentation and retrospective. That's ongoing. This doesn't mean it won't settle down. Heck, as it is, a lot of dynamic best practices influence the direction of non-dynamic languages - all of which arises from time and experimentation.