Closing Tags vs. Boolean Attributes: Guidance Seems To Contradict Intent

[RunnerRick]

The guidance for HTML closing tags and boolean attributes seems to be contradictory.

I'm referring to this text:

From https://github.com/thenerdery/html-css-standards/blob/master/standards/html.md#closing-tags:

Closing Tags

All elements should be closed via a tag pair or self closing declaration.

From https://github.com/thenerdery/html-css-standards/blob/master/standards/html.md#boolean-attributes:

Boolean Attributes

Boolean attributes should not have a value.

I assume the reason you would want empty elements (i.e. <input>, <br>) to be "self closing" (e.g. <input />, <br />) is so that an XML parser would parse the HTML source as a well-formed XML document.

However, if boolean attributes "should not have a value," then an XML parser would not consider the document well-formed. See https://stackoverflow.com/questions/6926442/is-an-xml-attribute-without-a-value-valid.

I can see the reason for dropping the value from boolean attributes, because it saves bytes, but if that is the reason, then you should also drop the self-closing declaration.

In other words it seems consistent to use either boolean attribute values with self-closing declarations or drop them both:

<input type="checkbox" selected="selected" />

OR

<input type="checkbox" selected>

NOT

<input type="checkbox" selected />

With that said, I'm open to learning the reasoning behind the guidance.

[ccheney]

I don't think there's a technical reason to self-close void tags if the doctype isn't xhtml. This standard is in place not to save bytes, but for readability and consistency amongst developers who are writing html.

[RunnerRick]

Thanks for the clarification.

[noahblon]

I agree with Rick. Self closing tags in HTML5 is a strange choice. It is not in line with industry convention and harms readability.