The 25 Boolean Attributes of HTML
Post from May 19, 2020, filed under Web Development.
There are Boolean attributes in HTML, and there are about two dozen of them—25, to be precise, unless I err somewhere. Here’s a quick rundown of what makes for a Boolean attribute, and what Boolean attributes there are in current HTML.
What is a Boolean at all? Citing the The Web Development Glossary, a Boolean is “a data type that has one of two possible values (usually denoted true and false).”
What is a Boolean attribute? A Boolean attribute is an attribute that can only be true or false.
How does a Boolean attribute work? According to the HTML specification:
The presence of a boolean attribute on an element represents the “true” value, and the absence of the attribute represents the “false” value.
Yet note:
The values “true” and “false” are not allowed on boolean attributes. To represent a false value, the attribute has to be omitted altogether.
So, what Boolean attributes are there?
The Boolean Attributes
allowfullscreen
allowpaymentrequest
async
autofocus
autoplay
checked
controls
default
disabled
formnovalidate
hidden
ismap
itemscope
loop
multiple
muted
nomodule
novalidate
open
playsinline
readonly
required
reversed
selected
truespeed
Yes. That’s it.
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I’m Jens Oliver Meiert, and I’m a web developer and author. I love trying things (including philosophy, art, and adventure). Here on meiert.com I share some of my views and experiences.
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Perhaps my most relevant book: CSS Optimization Basics (2018). Writing CSS is a craft. As craftspeople we strive to write high quality CSS. In CSS Optimization Basics I lay out some of the most important aspects of such CSS. (Also available in a bundle with Upgrade Your HTML and The Web Development Glossary.)
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