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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>
Web App Manifest
</title>
<script src="https://www.w3.org/Tools/respec/respec-w3c" class=
"remove"></script>
<script class='remove'>
var respecConfig = {
mdn: true,
previousPublishDate: "2013-12-17",
specStatus: "ED",
shortName: "appmanifest",
prevVersion: "FPWD",
previousMaturity: "WD",
formerEditors: [
{
name: "Rob Dolin",
company: "Microsoft Corporation",
companyURL: "https://www.microsoft.com/en-us/",
},
],
editors: [
{
name: "Marcos Cáceres",
company: "Mozilla Corporation",
companyURL: "https://mozilla.org/",
w3cid: 39125,
},
{
name: "Kenneth Rohde Christiansen",
company: "Intel Corporation",
companyURL: "https://intel.com/",
w3cid: 57705,
},
{
name: "Mounir Lamouri",
company: "Google Inc.",
companyURL: "https://www.google.com/",
w3cid: 45389,
},
{
name: "Anssi Kostiainen",
company: "Intel Corporation",
companyURL: "https://intel.com/",
w3cid: 41974,
},
{
name: "Matt Giuca",
company: "Google Inc.",
companyURL: "https://www.google.com/",
w3cid: 91260,
},
{
name: "Aaron Gustafson",
company: "Microsoft Corporation",
companyURL: "https://microsoft.com/",
w3cid: 43672,
},
],
group: "webapps",
github: "https://github.com/w3c/manifest/",
caniuse: {
feature: "web-app-manifest",
browsers: [
"chrome",
"firefox",
"safari",
"edge",
"and_chr",
"and_ff",
"ios_saf",
],
},
xref: "web-platform",
};
</script>
<style>
.icon-title {
text-transform: uppercase;
font-weight: bold;
}
.icons {
display: flex;
flex-direction: row;
flex-wrap: wrap;
}
.icons > figure {
text-align: left;
margin: 0;
padding: 10px;
width: 188px;
}
.icons > figure > img {
width: 188px;
height: 188px;
min-width: 188px;
min-height: 188px;
}
.icons > figure .icon-title {
display: block;
}
</style>
</head>
<body data-cite="ENCODING SCREEN-ORIENTATION MEDIAQUERIES-5">
<section id='abstract'>
<p>
This specification defines a JSON-based file format that provides
developers with a centralized place to put metadata associated with a
web application. This metadata includes, but is not limited to, the web
application's name, links to icons, as well as the preferred URL to
open when a user launches the web application. The manifest also allows
developers to declare a default screen orientation for their web
application, as well as providing the ability to set the display mode
for the application (e.g., in fullscreen). Additionally, the manifest
allows a developer to "scope" a web application to a URL. This
restricts the URLs to which the manifest is applied and provides a
means to "deep link" into a web application from other applications.
</p>
<p>
Using this metadata, user agents can provide developers with means to
create user experiences that are more comparable to that of a native
application.
</p>
</section>
<section id="sotd">
<div class="warning">
<p>
Implementors need to be aware that this specification is not stable.
However, aspects of this specification are shipping in at least one
browser (see links to implementation status at the top of this
document). <strong>Implementors who are not taking part in the
discussions will find the specification changing out from under them
in incompatible ways.</strong> Vendors interested in implementing
this specification before it eventually reaches the Candidate
Recommendation phase should <a href=
"https://github.com/w3c/manifest/issues">subscribe to the repository
on GitHub</a> and take part in the discussions.
</p>
</div>
</section>
<section class="informative">
<h2>
Usage Examples
</h2>
<p>
This section shows how developers can make use of the various features
of this specification.
</p>
<section class="informative">
<h3>
Example manifests
</h3>
<p>
The following shows a very simple <a>manifest</a>.
</p>
<pre class="example json" title="very simple manifest">
{
"name": "Donate App",
"description": "This app helps you donate to worthy causes.",
"icons": [{
"src": "images/icon.png",
"sizes": "192x192"
}]
}
</pre>
<p>
The following shows a more typical <a>manifest</a>.
</p>
<pre class="example json" title="typical manifest">
{
"lang": "en",
"dir": "ltr",
"name": "Super Racer 3000",
"short_name": "Racer3K",
"icons": [{
"src": "icon/lowres.webp",
"sizes": "64x64",
"type": "image/webp"
},{
"src": "icon/lowres.png",
"sizes": "64x64"
}, {
"src": "icon/hd_hi",
"sizes": "128x128"
}],
"scope": "/racer/",
"start_url": "/racer/start.html",
"display": "fullscreen",
"orientation": "landscape",
"theme_color": "aliceblue",
"background_color": "red"
}
</pre>
</section>
<section class="informative">
<h3>
Using a `link` element to link to a manifest
</h3>
<p>
The example also shows how to use the [=link type "manifest"=] and
how to use other [^meta^] and [^link^] elements to give the web
application a fallback name and set of icons.
</p>
<pre class="example html" title="linking to a manifest">
<!doctype>
<html>
<title>Racer 3K</title>
<!-- Startup configuration -->
<link rel="manifest" href="manifest.webmanifest">
<!-- Fallback application metadata for legacy browsers -->
<meta name="application-name" content="Racer3K">
<link rel="icon" sizes="16x16 32x32 48x48" href="lo_def.ico">
<link rel="icon" sizes="512x512" href="hi_def.png">
</pre>
<div data-cite="mimesniff" class="note" title=
"manifest.webmanifest or manifest.json?">
The official file extension for the manifest is `.webmanifest`. Some
web servers recognize this extension and transfer the file using the
standardized <a>application manifest MIME type</a>
([=application\/manifest+json=]). Developers can also choose a
different extension (e.g. `.json`) or none at all (e.g.
`/api/GetManifest`), but are encouraged to transfer the manifest
using the [=application\/manifest+json=] [=MIME type=], although any
[=JSON MIME type=] is ok.
</div>
</section>
</section>
<section>
<h2>
Installable web applications
</h2>
<p>
A common use case of a manifest is for a user agent to
<dfn data-local-lt="installing|installation" data-lt=
"installed">install</dfn> a web application; whereby the user agent
provides the end-user with a means of instantiating a new <a>top-level
browsing context</a> that has the manifest's members <a>applied</a> to
it. A web application that is installed is known as a <dfn data-export=
"">installed web application</dfn>. That is, the manifest's members, or
their defaults, are in effect on the <a>top-level browsing context</a>.
This distinguishes an installed web application from a traditional
bookmark, as opening a web page from a traditional bookmark will not
have the manifest's properties <a>applied</a> to it.
</p>
<p>
For example, on user agents that support installation, a web
application could be presented and launched in a way that, to the
end-user, is indistinguishable from native applications: such as
appearing as a labeled icon on the home screen, launcher, or start
menu. When launched, the manifest is <a>applied</a> by the user agent
to the <a>top-level browsing context</a> prior to the <a>start URL</a>
being loaded. This gives the user agent an opportunity to apply the
relevant values of the manifest, possibly changing the <a>display
mode</a> and screen orientation of the web application. Alternatively,
and again as an example, the user agent could <a>install</a> the web
application into a list of bookmarks within the user agent itself.
</p>
<p>
A [=document=] <dfn data-dfn-for="document">is installable</dfn> if
it's a [=top-level browsing context=] and the user agent deems it to be
installable (e.g., see [[[#installability-signals]]]).
</p>
<section>
<h3>
Authority of the manifest's metadata
</h3>
<p>
When a <a>manifest</a> is linked from a {{Document}}, it indicates to
the user agent that the metadata is <dfn>authoritative</dfn>: that
is, the user agent SHOULD use the metadata of the manifest instead of
the one in the {{Document}}. However, in cases where metadata is
missing, or in error, a user agent MAY fallback to the {{Document}}
to find suitable replacements for missing manifest members (e.g.,
using `application-name` in place of `short_name`).
</p>
</section>
<section data-link-for="WebAppManifest">
<h3>
Application's name
</h3>
<p>
The <dfn>application's name</dfn> is derived from either the
<a>name</a> member or <a>short_name</a> member (if either is present)
- otherwise, it is generated by the user agent or provided by the
end-user.
</p>
<p>
When either member is missing from the manifest, a user agent MAY use
the <a>name</a> member as a fallback for the <a>short_name</a> member
or vice versa.
</p>
<p>
If the <a>name</a> and <a>short_name</a> members are undefined, the
user agent SHOULD assign a default name (e.g., "Untitled") that
follows platform conventions. Alternatively, a user agent MAY allow
the end-user to input some text that can serve as the
<a>application's name</a>.
</p>
<p>
When both the <a>name</a> and <a>short_name</a> members are present,
it is left up to implementations to decide which member is best
suited for the space available (e.g., the <a>short_name</a> member
might be better suited for the space available underneath an icon).
</p>
</section>
<section>
<h3 id="installation-sec">
Privacy and security considerations
</h3>
<p>
It is RECOMMENDED that UI that affords the end user the ability to
<a>install</a> a web application also allows inspecting the icon,
name, <a>start URL</a>, origin, etc. pertaining to a web application.
This is to give an end-user an opportunity to make a conscious
decision to approve, and possibly modify, the information pertaining
to the web application before installing it. This also gives the
end-user an opportunity to discern if the web application is spoofing
another web application, by, for example, using an unexpected icon or
name.
</p>
<p>
It is RECOMMENDED that user agents prevent other applications from
determining which applications are installed on the system (e.g., via
a timing attack on the user agent's cache). This could be done by,
for example, invalidating from the user agent's cache the resources
linked to from the manifest (for example, icons) after a web
application is <a>installed</a> - or by using an entirely different
cache from that used for regular web browsing.
</p>
</section>
<section class="informative">
<h3 id="installability-signals">
Installability signals
</h3>
<p>
By design, this specification does not provide developers with an
explicit API to "install" a web application. Instead, a
<a>manifest</a> can serve as an <dfn>installability signal</dfn> to a
user agent that a web application can be <a>installed</a>.
</p>
<p>
Examples of <a>installability signals</a> for a web application:
</p>
<ul>
<li>has a <a>manifest</a> with at least a `name` member and a
suitable icon (e.g., of a particular format and of a minimum
width/height).
</li>
<li>is served over a secure network connection.
</li>
<li>has a sensible content security policy.
</li>
<li>is able to responsively adapt to display on a variety of screen
sizes, catering for both mobile and desktop.
</li>
<li>is able to function without a network connection.
</li>
<li>is repeatedly used by the end-user over some extended period of
time.
</li>
<li>has been explicitly marked by the user as one that they value and
trust (e.g., by bookmarking or "starring" it).
</li>
</ul>
<p>
This list is not exhaustive and some <a>installability signals</a>
might not apply to all user agents. How a user agent makes use of
these <a>installability signals</a> to determine if a web application
can be <a>installed</a> is left to implementers.
</p>
</section>
<section>
<h3>
Uninstallation
</h3>
<p>
User agents SHOULD provide a mechanism for the user to remove an
<a>installed web application</a> application.
</p>
<p>
It is RECOMMENDED that at the time of removal, the user agent also
present the user with an opportunity to revoke other persistent data
and settings associated with the application, such as permissions and
persistent storage.
</p>
</section>
</section>
<section>
<h2>
Navigation scope
</h2>
<p data-link-for="WebAppManifest">
The <dfn data-dfn-for="manifest" data-lt="navigation scope"
data-export="">navigation scope of a manifest</dfn> is the
{{WebAppManifest/scope}} member of a [=processed manifest=]. The
navigation scope restricts the set of URLs to which an [=application
context=] can be [=navigated=] while the manifest is [=applied=].
</p>
<div class="note" data-link-for="WebAppManifest">
<p>
If the <a>scope</a> member is not present in the manifest, it
defaults to the parent path of the <a>start_url</a> member. For
example, if <a>start_url</a> is <code>/pages/welcome.html</code>, and
<a>scope</a> is missing, the navigation scope will be
<code>/pages/</code> on the same origin. If <a>start_url</a> is
<code>/pages/</code> (the trailing slash is important!), the
navigation scope will be <code>/pages/</code>.
</p>
<p>
Developers should take care, if they rely on the default behavior,
that all of the application's page URLs begin with the parent path of
the start URL. To be safe, explicitly specify <a>scope</a>.
</p>
</div>
<p>
A [=URL=] |target:URL| is said to be <dfn data-dfn-for="URL"
data-export="">within scope</dfn> of [=URL=] |scope:URL| if the
following algorithm returns `true`:
</p>
<ol class="algorithm">
<li>If |target| and |scope| are not [=same origin=], return `false`.
</li>
<li>Let |scopePath:string| be the [=string/concatenation=] of
|scopes|'s [=URL/path=] using U+002F (/) as the separator.
</li>
<li>Let |targetPath:string| be the [=string/concatenation=] of
|target|'s [=URL/path=] using U+002F (/) as the separator.
</li>
<li>Return a [=boolean=] indicating whether |targetPath| starts with
|scopePath:string|.
</li>
</ol>
<p>
A [=URL=] |target:URL| is <dfn data-dfn-for="manifest" data-lt=
"within scope" data-export="">within scope</dfn> of a
|manifest:processed manifest| if the |target| is [=URL/within scope=]
of |manifest|'s [=manifest/navigation scope=] (i.e., [=URL/within
scope=] of |manifest|'s {{WebAppManifest/scope}} member).
</p>
<div class="note" title="Scope is a simple string match">
The URL string matching in this algorithm is prefix-based rather than
path-structural (e.g. a target URL string
<code>/prefix-of/resource.html</code> will match an app with scope
<code>/prefix</code>, even though the path segment name is not an exact
match). This is intentional for consistency with <a data-cite=
"SERVICE-WORKERS-1#scope-match-algorithm">Service Workers</a>. To avoid
unexpected behavior, use a scope ending in a <code>/</code>.
</div>
<p>
If the [=application context=]'s [=active document=]'s [=Document/URL=]
is not [=manifest/within scope=] of the [=application context=]'s
[=processed manifest=], the user agent SHOULD show a prominent UI
element indicating the [=Document/URL=] or at least its [=origin=],
including whether it is served over a secure connection. This UI SHOULD
differ from any UI used when the [=Document/URL=] is [=manifest/within
scope=] of the [=application context=]'s [=processed manifest=], in
order to make it obvious that the user is navigating off scope.
</p>
<div class="note">
<p>
Nothing prevents an <a>application context</a> from navigating to a
<a>URL</a> that is outside of the manifest's [=manifest/navigation
scope=], while still having the <a>manifest</a> <a>applied</a> to it.
</p>
<p>
Unlike previous versions of this specification, user agents are no
longer required or allowed to block off-scope navigations, or open
them in a new <a>top-level browsing context</a>. This practice broke
some sites that navigate to an off-scope URL (e.g., to perform
third-party authentication). See <a href=
"https://github.com/w3c/manifest/issues/646">Issue 646</a>.
</p>
</div>
<section data-link-for="DisplayModeType" class="informative">
<h3 id="navigation-scope-security-considerations">
Security considerations
</h3>
<p>
The above recommendation (to show some UI when the <a>application
context</a> is navigated to an out-of-scope <a>URL</a>) is for
security reasons. It ensures that users are always aware of which
<a>origin</a> they are interacting with.
</p>
<p>
Despite this, there is still a potential spoofing risk, if an
installed app pretends to navigate to an out-of-scope site on another
<a>origin</a>. The site shows a fake version of the user agent's
prominent out-of-scope UI, indicating to the user that it is on
another origin. However, in reality, the user has never navigated
away from the installed app's origin, and the user agent is not
showing any out-of-scope UI. User agents could try to show the
out-of-scope UI in a way that cannot be spoofed by the installed app.
However, due to the nature of the user agent's UI being minimal or
non-existent for installed apps, this may not be possible.
</p>
</section>
<section>
<h3>
Deep links
</h3>
<p>
A <dfn>deep link</dfn> is a URL that is [=manifest/within scope=] of
an [=installed web application=]'s [=processed manifest=].
</p>
<p>
An <a>application context</a> can be instantiated through a <a>deep
link</a>, in which case, the manifest is applied and the <a>deep
link</a> is loaded within the context of a web application.
</p>
<div class="note">
<p>
The concept of a <a>deep link</a> is useful in that it allows
hyperlinking from one <a>installed web application</a> to another.
This can be from a native application to an <a>installed web
application</a> (and possibly vice versa!). Theoretically, this can
provide seamless context switching between native and web
applications through standard hyperlinks. And in the case where a
particular web application is not <a>installed</a>, the OS can just
open the link in the user's preferred web browser.
</p>
<p>
Implementers are encouraged make such context switching obvious to
the user, for example, by adhering to the human interface
guidelines of the underlying platform with respect to application
switching.
</p>
</div>
</section>
</section>
<section data-dfn-for="DisplayModeType" data-link-for="DisplayModeType">
<h2>
Display modes
</h2>
<p>
A <dfn>display mode</dfn> represents how the web application is being
presented within the context of an OS (e.g., in fullscreen, etc.).
Display modes correspond to user interface (UI) metaphors and
functionality in use on a given platform. The UI conventions of the
display modes are purely advisory and implementers are free to
interpret them how they best see fit.
</p>
<p>
Once a user agent applies a particular <a>display mode</a> to an
<a>application context</a>, it becomes the <dfn>default display
mode</dfn> for the <a>top-level browsing context</a> (i.e., it is used
as the display mode when the window is <a>navigated</a>). The user
agent MAY override the <a>default display mode</a> for security reasons
(e.g., the <a>top-level browsing context</a> is <a>navigated</a> to
another origin) and/or the user agent MAY provide the user with a means
of switching to another <a>display mode</a>.
</p>
<p>
When the <a data-link-for="WebAppManifest">display</a> member is
missing, or if there is no valid <a data-link-for=
"WebAppManifest">display</a> member, the user agent uses the
<a>browser</a> <a>display mode</a> as the <a>default display mode</a>.
As such, the user agent MUST support the <a>browser</a> <a>display
mode</a>.
</p>
<p>
Each <a>display mode</a>, except <code>browser</code>, has a
<dfn>fallback display mode</dfn>, which is the <a>display mode</a> that
the user agent can try to use if it doesn't support a particular
<a>display mode</a>. If the user agent does support a <a>fallback
display mode</a>, then it checks to see if it can use that <a>display
mode</a>'s <a>fallback display mode</a>. This creates a fallback chain,
with the <a>default display mode</a> (<code>browser</code>) being the
last item in the chain.
</p>
<div class="example">
<p>
For example, SuperSecure Browser (a fictitious browser) only supports
the <code>minimal-ui</code> and <code>browser</code> display modes,
but a developer declares that she wants <code>fullscreen</code> in
the manifest. In this case, the user agent will first check if it
supports <code>fullscreen</code> (it doesn't), so it falls back to
<code>standalone</code> (which it also doesn't support), and
ultimately falls back to <code>minimal-ui</code>.
</p>
</div>
<p>
The <dfn>display modes values</dfn> defined by
<dfn>DisplayModeType</dfn>, and their corresponding <a>fallback display
modes</a> are as follows:
</p>
<dl>
<dt>
<dfn>fullscreen</dfn>
</dt>
<dd>
Opens the web application without any user agent chrome and takes up
the entirety of the available display area.
</dd>
<dd>
The <a>fallback display mode</a> for <code>fullscreen</code> is
<code>standalone</code>.
</dd>
<dt>
<dfn>standalone</dfn>
</dt>
<dd>
Opens the web application to look and feel like a standalone native
application. This can include the application having a different
window, its own icon in the application launcher, etc. In this mode,
the user agent will exclude standard browser UI elements such as an
URL bar, but can include other system UI elements such as a status
bar and/or system back button.
</dd>
<dd>
The <a>fallback display mode</a> for <code>standalone</code> is
<code>minimal-ui</code>.
</dd>
<dt>
<dfn>minimal-ui</dfn>
</dt>
<dd>
This mode is similar to <a>standalone</a>, but provides the end-user
with some means to access a minimal set of UI elements for
controlling navigation (i.e., back, forward, reload, and perhaps some
way of viewing the document's address). A user agent can include
other platform specific UI elements, such as "share" and "print"
buttons or whatever is customary on the platform and user agent.
</dd>
<dd>
The <a>fallback display mode</a> for <code>minimal-ui</code> is
<code>browser</code>.
</dd>
<dt>
<dfn>browser</dfn>
</dt>
<dd>
Opens the web application using the platform-specific convention for
opening hyperlinks in the user agent (e.g., in a browser tab or a new
window).
</dd>
<dd>
The <code>browser</code> <a>display mode</a> doesn't have a
<a>fallback display mode</a> (conforming user agents are required to
support the <code>browser</code> <a>display mode</a>).
</dd>
</dl>
<p class="note">
The <a>fullscreen</a> <a>display mode</a> is orthogonal to, and works
independently of, the [[[FULLSCREEN]]]. The <a>fullscreen</a>
<a>display mode</a> affects the fullscreen state of the browser window,
while the [[FULLSCREEN]] API operates on an element contained within
the viewport. As such, a web application can have its <a>display
mode</a> set to <a>fullscreen</a>, while
<code>document.fullScreenElement</code> returns <code>null</code>, and
<code>fullscreenEnabled</code> returns <code>false</code>.
</p>
<section>
<h3>
Privacy and security considerations
</h3>
<p>
When the web application is running, it is RECOMMENDED that the user
agent provides the end-user a means to access common information
about the web application, such as the origin, start and/or current
URL, granted permissions, and associated icon. How such information
is exposed to end-users is left up to implementers.
</p>
<p>
Additionally, when applying a manifest that sets the <a>display
mode</a> to anything except "<a>browser</a>", it is RECOMMENDED that
the user agent clearly indicate to the end-user that their are
leaving the normal browsing context of a web browser. Ideally,
launching or switching to a web application is performed in a manner
that is consistent with launching or switching to other applications
in the host platform. For example, a long and obvious animated
transition, or speaking the text "Launching application X".
</p>
</section>
<section data-link-for="DisplayModeType">
<h3>
The <code>'display-mode'</code> media feature
</h3>
<p>
The <code><dfn>display-mode</dfn></code> media feature represents,
via a CSS media query [[MEDIAQ]], the <a>display mode</a> of the web
application. This media feature applies to the top-level browsing
context and any child browsing contexts. Child browsing contexts
reflect the <a>display mode</a> of the <a>top-level browsing
context</a>.
</p>
<p>
A user agent MUST expose the '<code>display-mode</code>' media
feature irrespective of whether a manifest is being applied to a
browsing context. For example, if the end-user puts the whole user
agent into fullscreen, then the user agent would reflect this change
to CSS and scripts via the '<code>display-mode</code>' media feature.
</p>
<div class="note">
<p>
Please note that the <code>fullscreen</code> <a>display mode</a> is
not directly related to the CSS <code>:fullscreen</code>
pseudo-class specified in the [[[FULLSCREEN]]]. The
<code>:fullscreen</code> pseudo-class matches exclusively when a
[[HTML]] element is put into the fullscreen element stack. However,
a side effect of calling the <code>requestFullscreen()</code>
method on an element using the [[FULLSCREEN]] API is that the
browser window can enter a fullscreen mode at the OS-level. In such
a case, both <code>:fullscreen</code> and <code>(display-mode:
fullscreen)</code> will match.
</p>
<p>
On some platforms, it is possible for a user to put a browser
window into fullscreen without the aid of the [[[FULLSCREEN]]].
When this happens, the <code>:fullscreen</code> pseudo class will
not match, but <code>(display-mode: fullscreen)</code> will match.
This is exemplified in CSS code below.
</p>
<pre class='example'>
/* applies when the window is fullscreen */
@media all and (display-mode: fullscreen) {
...
}
/* applies when an element goes fullscreen */
#game:fullscreen {
...
}
</pre>
</div>
<dl>
<dt>
Value:
</dt>
<dd>
<a>fullscreen</a> | <a>standalone</a> | <a>minimal-ui</a> |
<a>browser</a>
</dd>
<dt>
Applies to:
</dt>
<dd>
visual media types
</dd>
<dt>
Accepts min/max prefixes:
</dt>
<dd>
No
</dd>
</dl>
<p>
A user agent MUST reflect the applied <a>display mode</a> of the web
application via a CSS media query [[MEDIAQ]].
</p>
<section>
<h4>
Examples
</h4>
<p>
An example in CSS:
</p>
<pre class="example js">
@media all and (display-mode: minimal-ui) {
/* ... */
}
@media all and (display-mode: standalone) {
/* ... */
}
</pre>
<p>
Accessing the display-mode media feature in ECMAScript through
<code>matchMedia()</code> of [[CSSOM-VIEW]]:
</p>
<pre class="example">
const standalone = matchMedia( '(display-mode: standalone)' );
standalone.onchange = (e) => {
/* handle changes to display mode */
}
if (standalone.matches) {
/* do standalone things */
}
</pre>
</section>
<section>
<h3>
Security and privacy considerations
</h3>
<p>
The <code>'display-mode'</code> media feature allows an origin
access to aspects of a user’s local computing environment and,
together with the <code>display</code> member, allows an origin
some measure of control over a user agent’s native UI: Through a
CSS media query, a script can know the display mode of a web
application. An attacker could, in such a case, exploit the fact
that an application is being displayed in fullscreen to mimic the
user interface of another application.
</p>
</section>
</section>
</section>
<section>
<h2>
Manifest life-cycle
</h2>
<p>
This section defines algorithms for [=processing a manifest=], and
<a>applying</a> a <a>manifest</a>.
</p>
<p>
A user agent MUST support the [=link type "manifest"=] and the
associated steps for how to fetch and process the linked resource.
</p>
<section id="processing" data-link-for="WebAppManifest">
<h3>
Processing the manifest
</h3>
<p>
When instructed to <dfn>issue a developer warning</dfn>, the user
agent MAY report the conformance violation to the developer in a
user-agent-specific manner (e.g., report the problem in an error
console), or MAY ignore the error and do nothing.
</p>
<p>
When instructed to <dfn>ignore</dfn>, the user agent MUST act as if
whatever manifest, member, or value caused the condition is absent.
</p>
<p>
The following algorithm provides an <dfn>extension point</dfn>: other
specifications that add new members to the manifest are encouraged to
hook themselves into this specification at this point in the
algorithm. They SHOULD NOT modify the existing values already in the
<var>manifest</var> object.
</p>
<div class="note">
<p>
The <a>extension point</a> is meant to help avoid <a href=
"https://annevankesteren.nl/2014/02/monkey-patch">issues related to
monkey patching</a>.
</p>
</div>
<p>
The steps for <dfn data-export="">processing a manifest</dfn> are
given by the following algorithm. The algorithm takes [^link^]
|el:HTMLLinkElement| and a [=Response=] |response|.
</p>
<ol>
<li>Let |json| be the result of [=parse JSON from bytes=]
|response|'s [=response/body=]. If parsing throws an error:
<ol>
<li>
<a>Issue a developer warning</a> with any details pertaining to
the JSON parsing error.
</li>
<li>Set <var>json</var> to an empty [=object=] (i.e., equivalent
of JSON parsing the string `"{}"`).
</li>
</ol>
</li>
<li>If |json| is not an [=ordered map=]:
<ol>
<li>
<a>Issue a developer warning</a> that the manifest needs to be
an object.
</li>
<li>Set <var>json</var> to an empty [=object=] (i.e., equivalent
of JSON parsing the string `"{}"`).
</li>
</ol>
</li>
<li>Let <var>manifest</var> be a new [=ordered map=].
</li>
<li>Set <var>manifest</var>["<a>start_url</a>"] to the result of
running <a>processing the <code>start_url</code> member</a> given
<var>json</var>["<a>start_url</a>"], <var>manifest URL</var>, and
<var>document URL</var>.
</li>
<li>Set <var>manifest</var>["<a>lang</a>"] to the result of running
<a>processing the <code>lang</code> member</a> given
<var>json</var>["<a>lang</a>"].
</li>
<li>Set <var>manifest</var>["<a>scope</a>"] to the result of running
<a>processing the <code>scope</code> member</a> given
<var>json</var>["<a>scope</a>"], <var>manifest URL</var>, and
<var>manifest</var>["<a>start_url</a>"].
</li>
<li>Set <var>manifest</var>["<a>theme_color</a>"] to the result of
running <a>processing a color member</a> given
<var>manifest</var>["<a>theme_color</a>"].
</li>
<li>Set <var>manifest</var>["<a>background_color</a>"] to the result
of running <a>processing a color member</a> given
<var>json</var>["<a>background_color</a>"].
</li>
<li>Set <var>manifest</var>["<a>icons</a>"] to the result of running
<a>processing `ManifestImageResource` members</a> given
<var>json</var>["<a>icons</a>"] and <var>manifest URL</var>.
</li>
<li>Set <var>manifest</var>["<a>related_applications</a>"] to the
result of running <a>processing the <code>related_applications</code>
member</a> given <var>json</var>["<a>related_applications</a>"].
</li>
<li>Run the <a>processing the <code>shortcuts</code> member</a> with
|manifest URL| and |manifest|.
</li>
<li>
<a>Extension point</a>: process any proprietary and/or other
supported members at this point in the algorithm.
</li>
<li>Let [=document=]'s <dfn>processed manifest</dfn> be a |manifest|.
</li>
</ol>
</section>
<section>
<h3 id="applying">
Applying the manifest
</h3>
<p>
A <a>processed manifest</a> is <dfn data-lt=
"apply|applying">applied</dfn> to a <a>top-level browsing
context</a>, meaning that the members of the <a>processed
manifest</a> are affecting the presentation or behavior of a browsing
context.
</p>
<p>
A <a>top-level browsing context</a> that has a manifest applied to it
is referred to as an <dfn>application context</dfn>.
</p>
<p>
If an <a>application context</a> is created as a result of the user
agent being asked to <a>navigate</a> to a <a>deep link</a>, the user
agent MUST immediately <a>navigate</a> to the <a>deep link</a> with
<a>replacement enabled</a>. Otherwise, when the <a>application
context</a> is created, the user agent MUST immediately
<a>navigate</a> to the <a>start URL</a> with <a>replacement
enabled</a>.
</p>
<div class="note">
<p>
The <a>start URL</a> is not necessarily the value of the
<a data-link-for="WebAppManifest"><code>start_url</code></a>
member: the user or user agent could have changed it when the
application was <a>installed</a>.
</p>
</div>
<p>
The appropriate time to <a>apply</a> a manifest is when the
<a>application context</a> is created and before
[=navigate|navigation=] to the <a>start URL</a> begins.
</p>
</section>
<section id="updating">
<h3>
Updating the manifest
</h3>
<div class="issue" data-number="446"></div>
</section>
</section>
<section data-cite="CSS-COLOR-4 CSS-SYNTAX-3">
<h2>
Color parsing
</h2>
<p>
The steps for <dfn>processing a color member</dfn> are given by the
following algorithm. The algorithm takes a <a>USVString</a>
<var>potential color</var> as an argument. This algorithm returns a
`USVString` or `undefined`.
</p>
<ol>
<li>Let |color| be the result of [=CSS/parsing=] |potential color| as a
CSS color.
</li>
<li>If |color| is failure:
<ol>
<li>
<a>Issue a developer warning</a> that |potential color| is not a
valid CSS color.
</li>
<li>Return `undefined`.
</li>
</ol>
</li>
<li>If |color| is an [=sRGB=] color, then return |color|.
</li>
<li>If |color| can be converted to [=sRGB=] using solely information
the user agent inherently knows, then convert it to [=sRGB=], and
return the result. Otherwise:
<ol>
<li>
<a>Issue a developer warning</a> that |potential color| is not a
supported color value.
</li>
<li>Return `undefined`.
</li>
</ol>