Last week I spoke at the very lovely Web Day Out in Brighton. My talk was about browser support, based on the work I’ve done over the past almost five years on Baseline. I ran through the various things you need to consider when deciding whether to use features that don’t meet your Baseline target. For example, if you are using Baseline Widely available as a target, how do you decide whether it’s “safe” to use a feature that’s still Baseline Newly available? One of the factors to consider, especially when planning a new project, is what will be part of your Baseline come launch day?

Newly available is the point of interoperability, a feature is part of Baseline the minute the last of the core browsers ships a stable version that includes it. From then the clock starts ticking until 30 months have passed and the feature becomes Baseline Widely available. For most people that’s the point at which they can use the feature without worrying about the fallback experience.

The data behind Baseline is what tells you if something is Newly or Widely available. It also gives you a new power, you can now look into the future of the web platform. If you are planning a project today, what’s the launch date? For a brand new site or application, that might be six months to a year from now. Rather than tying yourself to what’s Widely available today, you can probably include anything that will be Widely available on that date. The same is true of picking a different Baseline target based on a Baseline year. If Baseline 2023 makes sense today, and the new site will launch in nine months to a year, perhaps settle for Baseline 2024. Moving a year forward would give you features like Declarative Shadow DOM, @starting-style, and AVIF.

Whenever I talk about new features in CSS, people immediately ask when it will be available everywhere, or when it will be safe to use. The data gives you a way to understand that, and also to talk about the decisions with stakeholders. I think this is one of the most exciting things to come from this project, as we’ve never had this kind of future-facing view before.