WebExtensions - MDN Web Docs Glossary: Definitions of Web-related terms
webextensions is a cross-browser system for developing browser extensions in firefox.

Index
675 creating an appealing add-on listing add-ons, beginner, guide, webextension, publishing there are two essential steps to getting people to use your add-on: they need to discover your add-on and open the listing page, then the listing page needs to encourage them to click the add to firefox button.
... 676 index add-ons, glossary, guide, index found 689 pages: 677 signing and distributing your add-on add-ons, extensions, webextensions, distribution, publication, reviews, signing add-ons need to be signed before they can be installed into release and beta versions of firefox.
... 678 make money from browser extensions guide, monetization, webextensions, distribution while users can download browser extensions for firefox free of cost from addons.mozilla.org (amo), this doesn’t mean you can’t make money from browser extensions, and to a more limited extent themes.
...And 4 more matches

Install Manifests - Archive of obsolete content
note: the id property is optional in a webextension.
... 2 extensions 4 themes 8 locale 32 multiple item package 64 spell check dictionary 128 telemetry experiment 256 webextension experiment examples <em:type>2</em:type> this property was added for firefox 1.5, and is only required for add-on types other than extensions and themes.
... examples <em:developer>jane doe</em:developer> <em:developer>koos van der merwe</em:developer> hasembeddedwebextension if present and given the value "true", this indicates that this add-on contains an embedded webextension.
... <em:hasembeddedwebextension>true</em:hasembeddedwebextension> homepageurl a link to the add-on's home page - intended for display in the user interface.

Add-ons
developing extensions in the past, there were several toolsets for developing firefox extensions, but as of november 2017, extensions must be built using webextensions apis.
... extensions written using webextensions apis for firefox are designed to be cross-browser compatible.
...we are currently building support for the webextensions api on geckoview.
... migrate an existing extension if you maintain a legacy extension, such as an xul overlay, bootstrapped, or add-on sdk-based extension, you can still port it to use webextension apis.

The Firefox codebase: CSS Guidelines
in addition to this, firefox supports a variety of webextension themes that can be installed from amo.
... for testing purposes, here is an example of a webextension theme.
... never write css specially for the built-in light/dark theme in compacttheme.css unless that css isn't supposed to affect webextension themes.

package.json - Archive of obsolete content
hasembeddedwebextension new in jpm 1.2.0.
... boolean value: true if the add-on contains an embedded webextension.

Index - Archive of obsolete content
310 bookmarks.export() api, add-ons, bookmarks, extensions, method, non-standard, reference, webextensions, export exports bookmarks to an html bookmark file.
... 311 bookmarks.import() api, add-ons, bookmarks, extensions, method, non-standard, reference, webextensions, import imports bookmarks from an html bookmark file.

Deprecated tools - Firefox Developer Tools
although these panels have been removed, you still have access to the old code, and there are alternative webextensions that you can try to get similar functionality.
... alternatives spector.js is a webextension that can provide these features with 3d contexts.

about:debugging - Firefox Developer Tools
note: it's recommended that you use the browser toolbox, not the add-on debugger, for debugging webextensions.
... see debugging webextensions for all the details.

Index - Web APIs
1138 element.openorclosedshadowroot api, add-ons, element, extensions, mozilla, needs privileges, non-standard, property, reference, webextensions, openorclosedshadowroot, shadow dom the element.openorcloseshadowroot read-only property represents the shadow root hosted by the element, regardless if its mode is open or closed.
... 1990 history api advanced, dom, html5, history the dom window object provides access to the browser's session history (not to be confused for webextensions history) through the history object.

<iframe>: The Inline Frame element - HTML: Hypertext Markup Language
non-standard attributes mozbrowser see bug 1318532 for exposing this to webextensions in firefox.
... available only to webextensions.

chrome - Archive of obsolete content
this module should not be confused with the "chrome" global variable that webextensions can use to access apis.

Developing for Firefox Mobile - Archive of obsolete content
see developing webextensions for firefox for android to learn more about development of webextensions for firefox for android.

Appendix E: DOM Building and Insertion (HTML & XUL) - Archive of obsolete content
for webextensions the most simple way is sanitize the output about javascript inline declaration and other wrong content.

Index of archived content - Archive of obsolete content
.jsm prompt.jsm runtimepermissions.jsm snackbars.jsm sound.jsm tab addons developer guide code snippets creating a user interface firefox hub walkthrough initialization and cleanup prerequisites walkthrough webextensions for firefox for android listening to events in firefox extensions migrating from internal linkage to frozen linkage migrating raw components to add-ons multiple item extension packaging offering a context menu for form controls overlay extensions firefox addons dev...