[bug]: attributes seperated with non-breakable space not parsed properly

[chimurai]

A non-breakable space between attributes results in incorrect parsing:

<h1 tests foo="bar">My First Heading</h1>
         ^--- non-breakable space

current ast:

{
  "type": "tag",
  "name": "h1",
  "attribs": {
    "tests foo": "bar"
  }
}

expected ast:

{
  "type": "tag",
  "name": "h1",
  "attribs": {
    "tests": "",
    "foo": "bar"
  }
}

View AST online:
https://astexplorer.net/#/gist/d13142c629efe70f7b96ca3ff980890e/18c8e5c240f93bf3a45d0685bf399f398bfdfd33

non breakable space: https://en.wikipedia.org/wiki/Non-breaking_space
mac: alt + shift + space

Link to online AST with htmlparser2:

https://astexplorer.net/#/gist/d13142c629efe70f7b96ca3ff980890e/cf631a5987db518147e5d31687499701060db8d0

This issue is also present in the posthtml-parser, which uses htmlparser2:
posthtml/posthtml-parser#40

[fb55]

This seems in-line with what browsers do.

[chimurai]

Thanks for looking into to it.

Looks like non-breaking space (U+00A0) can be part of the attribute name.

https://html.spec.whatwg.org/multipage/syntax.html#attributes-2

Attributes have a name and a value. Attribute names must consist of one or more characters other than controls, U+0020 SPACE, U+0022 ("), U+0027 ('), U+003E (>), U+002F (/), U+003D (=), and noncharacters. In the HTML syntax, attribute names, even those for foreign elements, may be written with any mix of ASCII lower and ASCII upper alphas.

CSS behaves similarly:
https://jsfiddle.net/dzpqvx6r/