The implementations that are moving at all are keeping up fine. The biggest question for web developers is whether they support IE. If you do, you're stuck on E

The implementations that are moving at all are keeping up fine. The biggest question for web developers is whether they support IE. If you do, you're stuck on ES5. If not, you can use most features from ES2015 and up. Once the next release of Edge is out, that will expand greatly. Even if you support IE, you can still reap the benefits of modern JS if you're willing to do some differential serving. You can use the module/nomodule pattern to serve ES2017 without making changes to the server.