HTML element, attribute, and doctype name validation rules are changing #40366
Description
MDN URL
https://developer.mozilla.org/en-US/docs/Web/API/Element/setAttribute
What specific section or headline is this issue about?
https://developer.mozilla.org/en-US/docs/Web/API/Element/setAttribute#exceptions
What information was incorrect, unhelpful, or incomplete?
In
- Allow more characters when creating various nodes whatwg/dom#1079
- Allow more characters in custom element names whatwg/html#7991
- Remove more XML-derived attribute name validation whatwg/html#11453
we are changing the rules for validating various nodes.
This should affect:
createAttribute()createAttributeNS()setAttribute()setAttributeNS()toggleAttribute()createElement()createElementNS()createDocument()createDocumentType()customElements:define(),whenDefined()dataset's named property setter
I am not sure how many of these are documented on MDN. I found one, for setAttribute(), linked here. It might be good to search for all links to XML Name.
What did you expect to see?
Links to the new definitions in https://dom.spec.whatwg.org/#namespaces .
Do you have any supporting links, references, or citations?
No response
Do you have anything more you want to share?
No response
MDN metadata
Page report details
- Folder:
en-us/web/api/element/setattribute - MDN URL: https://developer.mozilla.org/en-US/docs/Web/API/Element/setAttribute
- GitHub URL: https://github.com/mdn/content/blob/main/files/en-us/web/api/element/setattribute/index.md
- Last commit: bcc977b
- Document last modified: 2025-07-04T17:14:36.000Z