Several planned code deprecations for Firefox 70, currently available on the Nightly pre-release channel, may impact extension and theme developers. Firefox 70 will be released on October 22, 2019.

In Firefox 65, we started deprecating the aliased theme properties accentcolor, textcolor, and headerURL. These properties will be removed in Firefox 70.

Themes listed on addons.mozilla.org (AMO) will be automatically updated to use supported properties. Most themes were updated back in April, but new themes have been created using the deprecated properties. If your theme is not listed on AMO, or if you are the developer of a dynamic theme, please update your theme’s manifest.json to use the supported properties.

In Firefox 70, the non-standard, Firefox-specific Array generic methods introduced with JavaScript 1.6 will be considered deprecated and scheduled for removal in the near future. For more information about which generics will be removed and suggested alternatives, please see the Firefox Site Compatibility blog.

The Site Compatibility team also intends to remove the non-standard prototype toSource and uneval by the end of 2019.

The post Upcoming deprecations in Firefox 70 appeared first on Mozilla Add-ons Blog.