With modern JS tooling, we have an opportunity to use Javascript features before they are implemented in browsers or node. However, not all features are equal. Some are more likely than others to be integrated into the language. Some will undergo significant changes before being added, and some will be dropped altogether. If you’re using that feature in your app, either of those can introduce big refactors. But how can you tell whether a feature is something you should use?
New features are introduced by TC39, a committee responsible for maintaining the specification underlying Javascript. There is a complete list of proposed additions to the spec in the TC39 proposals repo on GitHub. This is the canonical location for new features, the primary source. There is a well-defined process that proposals must go through, and learning more about that process will help you stay on the cutting edge.
The TC39 Process document defines what steps a proposal must take. This document is the source of the various stages that each feature goes through, which you may know best from the various stage-X presets from Babel. These stages are called the “maturity stages.” The table defining the stages is a quick read that will give you a ton of context for how much has gone into a given proposal.
