April 2021 web platform update

Now widely available on the web platform
Widely available

<output>: The <output> element represents the result of a calculation, user action, or form entry. Learn more.
Promise finally(): The promise finally() method executes a function when the promise settles (resolves or rejects). Learn more.
tabindex: The tabindex HTML attribute make an element focusable, and sets the element's relative ordering for sequential focus navigation. Learn more.

AudioWorklet: The AudioWorklet API runs module code in a separate thread, specifically for non-blocking, low latency audio processing. Learn more.
Flexbox gap: The gap CSS property in a flexbox layout sets the size of the space between items. Learn more.
Intl.DisplayNames: The Intl.DisplayNames API provides localized names of language, region, script, and currency codes. Learn more.
Intl.ListFormat: The Intl.ListFormat API creates a locale-aware formatter that turns iterable objects into localized strings. Learn more.
OfflineAudioContext: The OfflineAudioContext API represents an audio processing graph that writes to an AudioBuffer instead of an output device. Learn more.
Weak references: The WeakRef and FinalizationRegistry objects hold references to garbage-collectable objects without creating strong references that prevent their garbage collection. Learn more.
Web Audio: The Web Audio API creates graphs of audio nodes that handle sound inputs, synthesize sounds, apply effects, create visualizations, and output to audio devices. Learn more.