<url> type描述了< url-modifier>在
A URL is a pointer to a resource and is a functional notation@H_403_8@ denoted by
<url>. The Syntax of a<url>is:
<url> = url( <string> <url-modifier>* )In addition to the Syntax defined above,a can sometimes be@H_403_8@ written in other ways:
For legacy reasons,a
<url>can be written without quotation marks around the URL itself. This Syntax is specially-parsed,and@H_403_8@ produces a<url-token>rather than a function syntactically.@H_403_8@ [07001]Some CSS contexts,such as 07002,allow a
<url>to be represented by a 07003 instead. This behaves identically to@H_403_8@ writing aurl()function containing that string. Because these@H_403_8@ alternate ways of writing a<url>are not functional notations,they@H_403_8@ cannot accept any<url-modifier>s.Note: The special parsing rules for the legacy quotation mark-less@H_403_8@
<url>Syntax means that parentheses,whitespace characters,single@H_403_8@ quotes (‘) and double quotes (“) appearing in a URL must be escaped@H_403_8@ with a backslash,e.g.url(open\(parens),url(close\)parens).@H_403_8@ Depending on the type of URL,it might also be possible to write these@H_403_8@ characters as URL-escapes (e.g.url(open%28parens)or@H_403_8@url(close%29parens)) as described in[07004]. (If written as a@H_403_8@ normal function containing a string,ordinary string escaping rules@H_403_8@ apply; only newlines and the character used to quote the string need@H_403_8@ to be escaped.)
在
07005
The
url()function supports specifying additional<url-modifier>s,@H_403_8@ which change the meaning or the interpretation of the URL somehow. A@H_403_8@<url-modifier>is either an 07006 or a 07007.This specification does not define any
<url-modifier>s,but other@H_403_8@ 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？@H_403_8@>< string>之间有什么区别？ ，< ident>，在url()中的功能？
解决方法
A
<url-modifier>is either an<ident>or afunction.
< ident>是一个标识符。
A portion of the CSS source that has the same Syntax as an
<ident-token>.
我找不到任何< ident>的例子在url函数中使用但是@H_403_8@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@H_403_8@>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@H_403_8@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 {@H_403_8@background-image：url(“// aa.com/img.svg”prefetch);@H_403_8@}}
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)));}}
