What follows is a list of CSS selectors currently supported in latest NWSAPI version.

The list has been built upon current W3C Selectors Level 4 though it is still a work in progress.

Text and/or character selectors (content) have no meanings for applications, they don’t work on element nodes but on text nodes, which do not provide an event interface needed for selections.

* (asterisk)

any Element

E	an Element of type E
E#fooId	an E element with ID equal to “fooId”
E.fooClass	an E element with CLASS equal to “fooClass”

E:is(s1, s2, …)	an E element matching selectors s1 and/or s2 (Matches-Any)
E:not(s1, s2, …)	an E element not matching selectors s1 or s2 (Matches-None)

NOTE: the :is() pseudo-class is still named :matches() in most browsers implementation.

E F	an F element descendant child of an E element
E > F	an F element direct child of an E element
E + F	an F element immediately preceded by an E element
E ~ F	an F element preceded by an E element

E[foo]	an E element with a “foo” attribute
E[foo=“bar”]	an E element whose “foo” attribute value is exactly equal to bar
E[foo=“bar” i]	an E element whose “foo” attribute value is case insensitive match of bar
E[foo=“bar” s]	an E element whose “foo” attribute value is case sensitive match of bar
E[foo^=“bar”]	an E element whose “foo” attribute value begins exactly with the string bar
E[foo$=“bar”]	an E element whose “foo” attribute value ends exactly with the string bar
E[foo*=“bar”]	an E element whose “foo” attribute value contains the substring bar
E[foo|=“en”]	an E element whose “foo” attribute value is a hyphen-separated list beginning with en
E[foo~=“bar”]	an E element whose “foo” attribute value is a whitespace-separated list containing bar

E:root	an E element, root of the document
E:empty	an E element that has no children (including text nodes)
E:nth-child(n)	an E element, the n-th child of its parent
E:nth-of-type(n)	an E element, the n-th sibling of its type
E:nth-last-child(n)	an E element, the n-th child of its parent, counting from the last one
E:nth-last-of-type(n)	an E element, the n-th sibling of its type, counting from the last one
E:first-child	an E element, first child of its parent
E:last-child	an E element, last child of its parent
E:only-child	an E element, only child of its parent
E:first-of-type	an E element, first sibling of its type
E:last-of-type	an E element, last sibling of its type
E:only-of-type	an E element, only sibling of its type

E:link	an E element being the source anchor of an hyper-link never visited
E:visited	an E element being the source anchor of an hyper-link already visited
E:target	an E element being the target of the referring URI
E:scope	an E element being a designated reference element

E:dir(ltr)	an element of type E with left-to-right directionality
E:lang(it)	an element of type E tagged as being written in Italian

E:active	an E element during certain user actions
E:hover	an E element during a mouse over action
E:focus	an E element being the focus of the document
E:focus-within	an E element that has user input focus or contains an element that has input focus
E:focus-visible	an E element that has user input focus, and the UA has determined that a focus ring or other indicator should be drawn for that element

E:enabled	a user interface element E that is enabled
E:disabled	a user interface element E that is disabled
E:indeterminate	a user interface element E that is in an indeterminate state
E:default	a user interface element E that is the default item in a group
E:checked	a user interface element E that is checked or selected (radio or checkbox)
E:optional	a user-input element E that does not require input
E:required	a user-input element E that requires input
E:invalid	a user-input element E that does not meets its data validity semantics
E:valid	a user-input element E that meets its data validity semantics
E:in-range	a user-input element E whose value is in-range
E:out-of-range	a user-input element E whose value is out-of-range
E:read-only	a user interface element E that is not user alterable
E:read-write	a user interface element E that is user alterable

E::after	generated content after an E element
E::before	generated content before an E element
E::selection	portion of a document highlighted by the user
E::first-line	the first formatted line of an E element
E::first-letter	the first formatted letter of an E element