Firefox 71 for Developers

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This article provides information about the changes in Firefox 71 that will affect developers. Firefox 71 is the current Beta version of Firefox, and will ship on December 10, 2019.

Changes for web developers

Developer tools

No changes.

Removals

HTML

No changes.

 Removals

CSS

Removals

SVG

No changes.

Removals

JavaScript

  • The Promise.allSettled() method is now supported (bug 1549176). This method lets you easily wait until every promise in a set of promises has either resolved or rejected.

Removals

APIs

New APIs

DOM

DOM events

Service workers

Media, Web Audio, and WebRTC

Canvas and WebGL

Removals

The following non-standard DataTransfer members have been removed (bug 1345192):

Security

No changes.

Removals

Plugins

No changes.

Removals

Other

No changes.

Removals

Changes for add-on developers

API changes

  • downloads.download now identifies and reports as errors the following HTTP response codes:
    • 404 returning SERVER_BAD_CONTENT
    • 403 returning SERVER_FORBIDDEN
    • 402 and Proxy 407 returning SERVER_UNAUTHORIZED
    • Anything else above 400 returning SERVER_FAILED  (bug 1576333)
  • downloads.download now includes the optional options parameter property allowHttpErrors. When set to true, this boolean flag enables a download to continue after encountering an HTTP error otherwise, when set to false, a download is canceled when an HTTP error is encountered. Default value: false. (bug 1578955)

Removals

Manifest changes

No changes.

Removals

See also

Older versions