Update: namespace crash course #27662
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estelle
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(comment last updated: 2023-07-01 18:35:27) |
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| Note that namespace names are just strings, so the fact that the SVG namespace name also looks like a URI isn't important. URIs are commonly used because they are unique, the intention is not to "link" somewhere. (In fact URIs are used so frequently that the term "namespace URI" is commonly used instead of "namespace name".) | ||
| Note that namespace names are just strings, so the fact that the SVG namespace name also looks like a URI isn't important. URIs are commonly used because they are unique, the intention is not to "link" somewhere. (In fact, URIs are used so frequently that the term "namespace URI" is commonly used instead of "namespace name".) |
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I did not know that! I'd always wondered why rendering worked even if there was no fetch on the namespace URL.
| @@ -64,11 +66,11 @@ XML dialects not only define their own elements, but also their own parameters. | |||
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| This example has the rather unusual looking parameter `xmlns:xlink`. As you may guess from the first 'xmlns' part, this is another namespace declaration. However, instead of setting the default namespace, this namespace declaration sets the namespace for something called a "namespace prefix". In this case, we have chosen to use the prefix `xlink` (the second part) since the prefix will be used to tell the user agent about attributes that belong to XLink. | |||
| This example has the rather unusual-looking parameter `xmlns:xlink`. As you may guess from the first `xmlns` part, this is another namespace declaration. However, instead of setting the default namespace, this namespace declaration sets the namespace for something called a "[namespace prefix](/en-US/docs/Web/API/CSSNamespaceRule/prefix)". In this case, we have chosen to use the prefix `xlink` (the second part) since the prefix will be used to tell the user agent about attributes that belong to `XLink`. | |||
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Just FWIW, the namespace prefix link to a css rule on an SVG example looks a bit odd when reading the source. My assumption is that you chose this link and it makes sense to a reader.
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I find this weird too, especially since the prefix page is very brief as well.
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| As their name suggests, namespace prefixes are used to prefix parameter and element names. This is done by putting the namespace prefix and a colon before the parameter name as shown on the `<script>` element in the example above. This tells the user agent that the particular parameter belongs to the namespace assigned to the namespace prefix (XLink), and is a parameter that can be used with the same meaning on other elements. | ||
| As their name suggests, namespace prefixes are used to prefix parameter and element names. This is done by putting the namespace prefix and a colon before the parameter name as shown on the `<script>` element in the example above. This tells the user agent that the particular parameter belongs to the namespace assigned to the namespace prefix (`XLink`), and is a parameter that can be used with the same meaning on other elements. |
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Is it the "same meaning on other elements"? I understand that it is the same name, just confirming that if the same name is used in multiple specs it means the same thing.
hamishwillee
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Jun 30, 2023
OnkarRuikar
reviewed
Jun 30, 2023
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| #### Redeclaring the default namespace | ||
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| So if all the descendants of the root element are also defined to be in the default namespace, how do you mix in content from another namespace? Easy. You just redefine the default namespace. Here's a short example. | ||
| If all the descendants of the root element are also defined to be in the default namespace, how do you mix in content from another namespace? You redefine the default namespace! Here's a short example. |
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You redefine the default namespace!
In HTML, now the default namespaces are always implied and they are forced (you can't declare your own default namespace in the markup). So this entire section, from HTML point of view, has no utility left.
All it is doing now is asking developers to explicitly use xmlns attributes, which is not required.
I say we either
- remove the section
Redeclaring the default namespacecompletely - or make it discuss about XML, where it still applies:
<report xmlns="www.acme.org/reports> <title>Some stats</title> <summary>...</summary> <statTable xmlns="www.acme.org/tables> <content>...</content> <summary xmlns="www.acme.org/reports">...</summary> <!-- redeclaring root's default namespace --> </statTable> </report>
On MDN do we consider XML while discussing CSS? or just HTML?
Co-authored-by: Hamish Willee <hamishwillee@gmail.com>
estelle
commented
Jul 1, 2023
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| See, namespaces really aren't that hard. | ||
| This example was for illustrative purposes only. With HTML, `http://www.w3.org/1999/xhtml` is the implied namespace. It does not need to be explicitly declared. |
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Suggested change
| This example was for illustrative purposes only. With HTML, `http://www.w3.org/1999/xhtml` is the implied namespace. It does not need to be explicitly declared. | |
| This example was for illustrative purposes only. With HTML, `http://www.w3.org/1999/xhtml` is the implied namespace. It does not need to be explicitly declared. In HTML, the default namespaces are always implied and are forced, meaning you can't redeclare a different default namespace in the markup |
Co-authored-by: Onkar Ruikar <87750369+OnkarRuikar@users.noreply.github.com>
Co-authored-by: Onkar Ruikar <87750369+OnkarRuikar@users.noreply.github.com>
Co-authored-by: Onkar Ruikar <87750369+OnkarRuikar@users.noreply.github.com>
Co-authored-by: Joshua Chen <sidachen2003@gmail.com>
Co-authored-by: Joshua Chen <sidachen2003@gmail.com>
Co-authored-by: Joshua Chen <sidachen2003@gmail.com>
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Only added a single link to CSS namespace API. after namespace documentation is complete will add a few more links, but that is a future PR