Changing Feature Flag settings in Safari on macOS
Test new web platform features before they ship in Safari.
Overview
The web is constantly evolving with new features and technologies. It can be exciting to see potential future tools and technologies, and even more exciting to begin experimenting with them before they ship in web browsers.
Safari lets you enable these features using the new Feature Flags settings, which can be opened from the Develop menu by choosing Feature Flags….
Features are organized by topic, like Animation, CSS, JavaScript, Media, and more, making it easy to find related features. They can also be searched by both feature name and status.
When you toggle a feature to a non-default state, its name is displayed in bold.
Feature Statuses
There are four possible statuses for a feature, each with a different meaning and default state. Non-developer features will typically start as Testable features, and then move to Preview as the feature and spec the feature is based on matures, eventually becoming Stable features.
- Stable
Stable features are features that have recently begun shipping in Safari and are on by default. These feature can be toggled to help determine if a feature is causing an issue, or to make sure your site still gracefully handles the absence of the feature for features not yet shipping in all browsers. Stable features will eventually be removed from the list of feature flags.
- Preview
Preview features are features that are ready for developers to begin experimenting with. While these features are disabled by default in Safari, they are enabled by default in Safari Technology Preview.
- Testable
Testable features are those that are not ready for use, but that may be ready for early feedback. Testable features can help inform the standards the feature is based on to make sure the spec works for web developers. These features are disabled by default.
- Developer
Developer features can be settings that adjust the behavior of WebKit for development, reenable deprecated API for testing, or enable an extra tool like Media Stats. These features are disabled by default.