This specification is like no other — it has been processed with you, the humble web developer, in mind.
The focus of this specification is readability and ease of access. Unlike the full HTML Standard, this "developer's edition" removes information that only browser vendors need know. It is automatically produced from the full specification by our build tooling, and thus always in sync with the latest developments in HTML.
To read about its conception, construction, and future, read the original press release, and the blog post about its relaunch.
Finally, feel free to contribute on GitHub to make this edition better for everyone!
A string is a valid non-empty URL if it is a valid URL string but it is not the empty string.
A string is a valid URL potentially surrounded by spaces if, after stripping leading and trailing ASCII whitespace from it, it is a valid URL string.
A string is a valid non-empty URL potentially surrounded by spaces if, after stripping leading and trailing ASCII whitespace from it, it is a valid non-empty URL.
This specification defines the URL about:legacy-compat
as a reserved,
though unresolvable, about:
URL, for use in DOCTYPEs in HTML documents when needed for
compatibility with XML tools. [ABOUT]
This specification defines the URL about:html-kind
as a reserved,
though unresolvable, about:
URL, that is used as an
identifier for kinds of media tracks. [ABOUT]
This specification defines the URL about:srcdoc
as a reserved, though
unresolvable, about:
URL, that is used as the URL of iframe
srcdoc
documents.
[ABOUT]
The fallback base URL of a Document
object document is the
URL record obtained by running these steps:
If document is an iframe
srcdoc
document, then return the document base
URL of document's browsing context's
browsing context container's node document.
If document's URL is
about:blank
, and document's browsing
context has a creator browsing context, then return the creator base
URL.
Return document's URL.
The document base URL of a Document
object is the
absolute URL obtained by running these steps:
If there is no base
element that has an href
attribute in the Document
, then the
document base URL is the Document
's fallback base URL;
abort these steps.
Otherwise, the document base URL is the frozen base URL of the
first base
element in the Document
that has an href
attribute, in tree order.
A CORS settings attribute is an enumerated attribute. The following table lists the keywords and states for the attribute — the keywords in the left column map to the states in the cell in the second column on the same row as the keyword.
Keyword | State | Brief description |
---|---|---|
anonymous
| Anonymous | Requests for the element will have their mode set to "cors " and their credentials mode set to "same-origin ".
|
use-credentials
| Use Credentials | Requests for the element will have their mode set to "cors " and their credentials mode set to "include ".
|
The empty string is also a valid keyword, and maps to the Anonymous state. The attribute's invalid value default is the Anonymous state. For the
purposes of reflection, the canonical case for the Anonymous state is the anonymous
keyword. The missing value default, used when the attribute is omitted, is the No
CORS state.
A referrer policy attribute is an enumerated attribute. Each referrer policy, including the empty string, is a keyword for this attribute, mapping to a state of the same name.
The attribute's invalid value default and missing value default are both the empty string state.
The impact of these states on the processing model of various fetches is defined in more detail throughout this specification, in the WHATWG Fetch standard, and in Referrer Policy. [FETCH] [REFERRERPOLICY]
Several signals can contribute to which processing model is used for a given fetch; a referrer policy attribute is only one of them. In general, the order in which these signals are processed are:
First, the presence of a noreferrer
link
type;
Then, the value of a referrer policy attribute;
Then, the presence of any meta
element with name
attribute set to referrer
.
Finally, the `Referrer-Policy
` HTTP
header.