Boolean attribute (HTML)

A boolean attribute in HTML is an attribute that can be either true or false.

It is worth noticing that a boolean attribute is true when it is present, and false when it is absent.

Here's an example of a HTML boolean attribute checked:

html

<!-- The following checkboxes will be checked on initial rendering -->
<input type="checkbox" checked />
<input type="checkbox" checked="" />
<input type="checkbox" checked="true" />
<input type="checkbox" checked="false" />
<input type="checkbox" checked="any value" />

<!-- The following checkbox will not be checked on initial rendering -->
<input type="checkbox" />