<url> type描述了< url-modifier>在
A URL is a pointer to a resource and is a functional notation
denoted by<url>@H_502_10@. The Syntax of a<url>@H_502_10@ is:
<url> = url( <string> <url-modifier>* )@H_502_10@In addition to the Syntax defined above,a can sometimes be
written in other ways:
For legacy reasons,a
<url>@H_502_10@ can be written without quotation marks around the URL itself. This Syntax is specially-parsed,and
produces a<url-token>@H_502_10@ rather than a function syntactically.
[07001]Some CSS contexts,such as 07002,allow a
<url>@H_502_10@ to be represented by a 07003 instead. This behaves identically to
writing aurl()@H_502_10@ function containing that string. Because these
alternate ways of writing a<url>@H_502_10@ are not functional notations,they
cannot accept any<url-modifier>@H_502_10@s.Note: The special parsing rules for the legacy quotation mark-less
<url>@H_502_10@ Syntax means that parentheses,whitespace characters,single
quotes (‘) and double quotes (“) appearing in a URL must be escaped
with a backslash,e.g.url(open\(parens)@H_502_10@,url(close\)parens)@H_502_10@.
Depending on the type of URL,it might also be possible to write these
characters as URL-escapes (e.g.url(open%28parens)@H_502_10@ or
url(close%29parens)@H_502_10@) as described in[07004]. (If written as a
normal function containing a string,ordinary string escaping rules
apply; only newlines and the character used to quote the string need
to be escaped.)
在
07005
The
url()@H_502_10@ function supports specifying additional<url-modifier>@H_502_10@s,
which change the meaning or the interpretation of the URL somehow. A
<url-modifier>@H_502_10@ is either an 07006 or a 07007.This specification does not define any
<url-modifier>@H_502_10@s,but other
specs may do so.
参见CSS Values and Units Module Level 3
Editor’s Draft,21 March 2016
>什么是< ident>的示例用法并在url()函数？
>< string>之间有什么区别？ ，< ident>，在url()中的功能？
解决方法
A
<url-modifier>@H_502_10@ is either an<ident>@H_502_10@ or afunction@H_502_10@.
< ident>是一个标识符。
A portion of the CSS source that has the same Syntax as an
<ident-token>@H_502_10@.
我找不到任何< ident>的例子在url函数中使用但是
如this email所述，有一些可能的未来用途。
>提取选项来控制CORS / cookies / etc
>使用子资源完整性
查看< ident>语法你不能使用键/值对，所以我假设
其中大部分将使用尚不存在的功能实现，资源提示可以使用< ident> ;.实现。 .foo {
background-image：url(“// aa.com/img.svg”prefetch);
}}
然而，我找到了一个“有趣的想法的集合”，其功能是< url-modifier>定义。
SVG Parameters(不是官方规格)
.foo {background-image：url(“// aa.com/img.svg”param( – color var( – primary-color)));}}
