Deprecated

For a given set of browsers, what APIs are removed in all of them how many days it take for the API to removed in the first browser to the last.

Example Comparisons
Browsers
Features

Summary

A count of the number of APIs that were removed from A first and B last.
Last removed from SafariLast removed from Firefox
First removed from Safari 3
First removed from Firefox 9

Average time for an API to be removed across Safari and Firefox

12 APIs took an average of 1583.59 days to be removed

API breakdown:

Average time to landing by year of first deprecation

If a feature is deprecated in the earliest browser in 20XX it took Y days on average to become deprecated in the last browser (when considering Safari and Firefox). TTA (time to available).
HTML APIsHTML TTADOM API APIsDOM API TTA
2012 0NaN14990.18
2016 0NaN13590.18
2017 0NaN13464.18
2020 12309.180NaN
2021 0NaN11911.18
2025 0NaN7391.18

Deprecated APIs

Below is a list of features that are deprecated in Safari and Firefox

Raw Data

Quick Links:

DOM API Data

API First Browser Date Last Browser Date Days Notes
api.CSSStyleDeclaration.cssFloat 📋Firefox11/20/2012 Safari9/15/2025
api.File.lastModifiedDate Safari9/20/2016 Firefox6/26/2018
api.MutationEvent Firefox6/24/2025 Safari9/15/2025
api.MutationEvent.attrChange Firefox6/24/2025 Safari9/15/2025
api.MutationEvent.attrName Firefox6/24/2025 Safari9/15/2025
api.MutationEvent.initMutationEvent Firefox6/24/2025 Safari9/15/2025
api.MutationEvent.newValue Firefox6/24/2025 Safari9/15/2025
api.MutationEvent.prevValue Firefox6/24/2025 Safari9/15/2025
api.MutationEvent.relatedNode Firefox6/24/2025 Safari9/15/2025
api.RTCPeerConnection.removeStream Firefox1/24/2017 Safari9/17/2018
api.SpeechSynthesisEvent.elapsedTime.milliseconds Safari4/26/2021 Firefox12/7/2021
Firefox: Windows and macOS only.

HTML Data

API First Browser Date Last Browser Date Days Notes
html.elements.object.codebase 📋Safari3/24/2020 Firefox8/19/2025