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+Title: window.browser
+Shortname: wecg-browser
+Level: 1
+Group: wecg
+Status: UD
+URL: https://w3c.github.io/webextensions/specification/window.browser.html
+Editor: Patrick Kettner, Google, patrickkettner@google.com
+Abstract: This specification reserves the window.browser namespace for use by WebExtensions.
+Repository: w3c/webextensions
+Complain About: accidental-2119 on, missing-example-ids on
+
+
+
+ ## Introduction
+ This section is non-normative.
+
+ Browser extensions are programs to extend the capabilities of web browsers.
+ Although not standardized at first, web browsers have independently implemented a common interoperable set of extension APIs, called WebExtensions.
+
+ Modern WebExtensions are an evolution of a system originally introduced in
+ Chromium. In that system, any API that was added was put under the
+ chrome namespace. When WebExtensions were adopted outside of
+ Chromium, other vendors used the more neutral browser namespace.
+ That browser is now considered the canonically correct namespace
+ for all WebExtension APIs. Some interactions with WebExtensions (such as
+ external messaging from websites to background processes) necessitate
+ the exposure of this namespace to the web.
+
+ Given that, this document defines window.browser as reserved for
+ the use of APIs designed to interact with WebExtensions. The specifics of what
+ APIs within window.browser are at present intentionally undefined,
+ and are left up to User Agent implementation.
+
+
+
+
+
+
+ {{browser}} is UA defined attribute exposed on {{window}}. When implemented,
+ it MUST be used only for WebExtension related functionality.
+
+
+
+
+
+ When {{browser}} is defined on {{window}}, it SHOULD also be exposed on {{ServiceWorkerGlobalScope}}
+ of origins associated with WebExtensions.
+ It MUST be used exclusively for WebExtension purposes, however the contents of each instance of {{browser}} is UA defined.
+
+
+
Browser extensions are programs to extend the capabilities of web browsers.
+ Although not standardized at first, web browsers have independently implemented a common interoperable set of extension APIs, called WebExtensions.
+
Modern WebExtensions are an evolution of a system originally introduced in
+ Chromium. In that system, any API that was added was put under the chrome namespace. When WebExtensions were adopted outside of
+ Chromium, other vendors used the more neutral browser namespace.
+ That browser is now considered the canonically correct namespace
+ for all WebExtension APIs. Some interactions with WebExtensions (such as
+ external messaging from websites to background processes) necessitate
+ the exposure of this namespace to the web.
+
Given that, this document defines window.browser as reserved for
+ the use of APIs designed to interact with WebExtensions. The specifics of what
+ APIs within window.browser are at present intentionally undefined,
+ and are left up to User Agent implementation.
When browser is defined on window, it SHOULD also be exposed on ServiceWorkerGlobalScope of origins associated with WebExtensions.
+ It MUST be used exclusively for WebExtension purposes, however the contents of each instance of browser is UA defined.
Conformance requirements are expressed
+ with a combination of descriptive assertions
+ and RFC 2119 terminology.
+ The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL”
+ in the normative parts of this document
+ are to be interpreted as described in RFC 2119.
+ However, for readability,
+ these words do not appear in all uppercase letters in this specification.
+
All of the text of this specification is normative
+ except sections explicitly marked as non-normative, examples, and notes. [RFC2119]
+
Examples in this specification are introduced with the words “for example”
+ or are set apart from the normative text
+ with class="example",
+ like this:
+
+
+
This is an example of an informative example.
+
+
Informative notes begin with the word “Note”
+ and are set apart from the normative text
+ with class="note",
+ like this: