Mojo::DOM::CSS(3pm)

NAME
Mojo::DOM::CSS - CSS selector engine

SYNOPSIS
  use Mojo::DOM::CSS;

  # Select elements from DOM tree
  my $css = Mojo::DOM::CSS->new(tree => $tree);
  my $elements = $css->select('h1, h2, h3');

DESCRIPTION
Mojo::DOM::CSS is the CSS selector engine used by Mojo::DOM, based on the HTML Living Standard <https://html.spec.whatwg.org> and Selectors Level 3 <https://www.w3.org/TR/css3-selectors/>.

SELECTORS
All CSS selectors that make sense for a standalone parser are supported.

  *
Any element.

  my $all = $css->select('*');

  E
An element of type "E".

  my $title = $css->select('title');

  E[foo]
An "E" element with a "foo" attribute.

  my $links = $css->select('a[href]');

  E[foo="bar"]
An "E" element whose "foo" attribute value is exactly equal to "bar".

  my $case_sensitive = $css->select('input[type="hidden"]');
  my $case_sensitive = $css->select('input[type=hidden]');

  E[foo="bar" i]
An "E" element whose "foo" attribute value is exactly equal to any (ASCII-range) case-permutation of "bar". Note that this selector is EXPERIMENTAL and might change without warning!

  my $case_insensitive = $css->select('input[type="hidden" i]');
  my $case_insensitive = $css->select('input[type=hidden i]');
  my $case_insensitive = $css->select('input[class~="foo" i]');

This selector is part of Selectors Level 4 <https://dev.w3.org/csswg/selectors-4>, which is still a work in progress.

  E[foo="bar" s]
An "E" element whose "foo" attribute value is exactly and case-sensitively equal to "bar". Note that this selector is EXPERIMENTAL and might change without warning!

  my $case_sensitive = $css->select('input[type="hidden" s]');

This selector is part of Selectors Level 4 <https://dev.w3.org/csswg/selectors-4>, which is still a work in progress.

  E[foo~="bar"]
An "E" element whose "foo" attribute value is a list of whitespace-separated values, one of which is exactly equal to "bar".

  my $foo = $css->select('input[class~="foo"]');
  my $foo = $css->select('input[class~=foo]');

  E[foo^="bar"]
An "E" element whose "foo" attribute value begins exactly with the string "bar".

  my $begins_with = $css->select('input[name^="f"]');
  my $begins_with = $css->select('input[name^=f]');

  E[foo$="bar"]
An "E" element whose "foo" attribute value ends exactly with the string "bar".

  my $ends_with = $css->select('input[name$="o"]');
  my $ends_with = $css->select('input[name$=o]');

  E[foo*="bar"]
An "E" element whose "foo" attribute value contains the substring "bar".

  my $contains = $css->select('input[name*="fo"]');
  my $contains = $css->select('input[name*=fo]');

  E[foo|="en"]
An "E" element whose "foo" attribute has a hyphen-separated list of values beginning (from the left) with "en".

  my $english = $css->select('link[hreflang|=en]');

  E:root
An "E" element, root of the document.

  my $root = $css->select(':root');

  E:nth-child(n)
An "E" element, the "n-th" child of its parent.

  my $third = $css->select('div:nth-child(3)');
  my $odd   = $css->select('div:nth-child(odd)');
  my $even  = $css->select('div:nth-child(even)');
  my $top3  = $css->select('div:nth-child(-n+3)');

  E:nth-last-child(n)
An "E" element, the "n-th" child of its parent, counting from the last one.

  my $third    = $css->select('div:nth-last-child(3)');
  my $odd      = $css->select('div:nth-last-child(odd)');
  my $even     = $css->select('div:nth-last-child(even)');
  my $bottom3  = $css->select('div:nth-last-child(-n+3)');

  E:nth-of-type(n)
An "E" element, the "n-th" sibling of its type.

  my $third = $css->select('div:nth-of-type(3)');
  my $odd   = $css->select('div:nth-of-type(odd)');
  my $even  = $css->select('div:nth-of-type(even)');
  my $top3  = $css->select('div:nth-of-type(-n+3)');

  E:nth-last-of-type(n)
An "E" element, the "n-th" sibling of its type, counting from the last one.

  my $third    = $css->select('div:nth-last-of-type(3)');
  my $odd      = $css->select('div:nth-last-of-type(odd)');
  my $even     = $css->select('div:nth-last-of-type(even)');
  my $bottom3  = $css->select('div:nth-last-of-type(-n+3)');

  E:first-child
An "E" element, first child of its parent.

  my $first = $css->select('div p:first-child');

  E:last-child
An "E" element, last child of its parent.

  my $last = $css->select('div p:last-child');

  E:first-of-type
An "E" element, first sibling of its type.

  my $first = $css->select('div p:first-of-type');

  E:last-of-type
An "E" element, last sibling of its type.

  my $last = $css->select('div p:last-of-type');

  E:only-child
An "E" element, only child of its parent.

  my $lonely = $css->select('div p:only-child');

  E:only-of-type
An "E" element, only sibling of its type.

  my $lonely = $css->select('div p:only-of-type');

  E:empty
An "E" element that has no children (including text nodes).

  my $empty = $css->select(':empty');

  E:any-link
Alias for "E:link". Note that this selector is EXPERIMENTAL and might change without warning! This selector is part of Selectors Level 4 <https://dev.w3.org/csswg/selectors-4>, which is still a work in progress.

  E:link
An "E" element being the source anchor of a hyperlink of which the target is not yet visited (":link") or already visited (":visited"). Note that Mojo::DOM::CSS is not stateful, therefore ":any-link", ":link" and ":visited" yield exactly the same results.

  my $links = $css->select(':any-link');
  my $links = $css->select(':link');
  my $links = $css->select(':visited');

  E:visited
Alias for "E:link".

  E:scope
An "E" element being a designated reference element. Note that this selector is EXPERIMENTAL and might change without warning!

  my $scoped = $css->select('a:not(:scope > a)');
  my $scoped = $css->select('div :scope p');
  my $scoped = $css->select('~ p');

This selector is part of Selectors Level 4 <https://dev.w3.org/csswg/selectors-4>, which is still a work in progress.

  E:checked
A user interface element "E" which is checked (for instance a radio-button or checkbox).

  my $input = $css->select(':checked');

  E.warning
An "E" element whose class is "warning".

  my $warning = $css->select('div.warning');

  E#myid
An "E" element with "ID" equal to "myid".

  my $foo = $css->select('div#foo');

  E:not(s1, s2)
An "E" element that does not match either compound selector "s1" or compound selector "s2". Note that support for compound selectors is EXPERIMENTAL and might change without warning!

  my $others = $css->select('div p:not(:first-child, :last-child)');

Support for compound selectors was added as part of Selectors Level 4 <https://dev.w3.org/csswg/selectors-4>, which is still a work in progress.

  E:is(s1, s2)
An "E" element that matches compound selector "s1" and/or compound selector "s2". Note that this selector is EXPERIMENTAL and might change without warning!

  my $headers = $css->select(':is(section, article, aside, nav) h1');

This selector is part of Selectors Level 4 <https://dev.w3.org/csswg/selectors-4>, which is still a work in progress.

  E:has(rs1, rs2)
An "E" element, if either of the relative selectors "rs1" or "rs2", when evaluated with "E" as the :scope elements, match an element. Note that this selector is EXPERIMENTAL and might change without warning!

  my $link = $css->select('a:has(> img)');

This selector is part of Selectors Level 4 <https://dev.w3.org/csswg/selectors-4>, which is still a work in progress. Also be aware that this feature is currently marked "at-risk", so there is a high chance that it will get removed completely.

  E:text(string_or_regex)
An "E" element containing text content that substring matches "string_or_regex" case-insensitively or that regex matches "string_or_regex". For regular expressions use the format :text(/.../). Note that this selector is EXPERIMENTAL and might change without warning!

  # Substring match
  my $login = $css->select(':text(Log in)');

  # Regex match
  my $login = $css->select(':text(/Log ?in/)');

  # Regex match (case-insensitive)
  my $login = $css->select(':text(/(?i:Log ?in)/)');

This is a custom selector for Mojo::DOM and not part of any spec.

  A|E
An "E" element that belongs to the namespace alias "A" from CSS Namespaces Module Level 3 <https://www.w3.org/TR/css-namespaces-3/>. Key/value pairs passed to selector methods are used to declare namespace aliases.

  my $elem = $css->select('lq|elem', lq => 'http://example.com/q-markup');

Using an empty alias searches for an element that belongs to no namespace.

  my $div = $c->select('|div');

  E F
An "F" element descendant of an "E" element.

  my $headlines = $css->select('div h1');

  E > F
An "F" element child of an "E" element.

  my $headlines = $css->select('html > body > div > h1');

  E + F
An "F" element immediately preceded by an "E" element.

  my $second = $css->select('h1 + h2');

  E ~ F
An "F" element preceded by an "E" element.

  my $second = $css->select('h1 ~ h2');

  E, F, G
Elements of type "E", "F" and "G".

  my $headlines = $css->select('h1, h2, h3');

  E[foo=bar][bar=baz]
An "E" element whose attributes match all following attribute selectors.

  my $links = $css->select('a[foo^=b][foo$=ar]');

ATTRIBUTES
Mojo::DOM::CSS implements the following attributes.

  tree
  my $tree = $css->tree;
  $css     = $css->tree(['root']);

Document Object Model. Note that this structure should only be used very carefully since it is very dynamic.

METHODS
Mojo::DOM::CSS inherits all methods from Mojo::Base and implements the following new ones.

  matches
  my $bool = $css->matches('head > title');
  my $bool = $css->matches('svg|line', svg => 'http://www.w3.org/2000/svg');

Check if first node in "tree" matches the CSS selector. Trailing key/value pairs can be used to declare xml namespace aliases.

  select
  my $results = $css->select('head > title');
  my $results = $css->select('svg|line', svg => 'http://www.w3.org/2000/svg');

Run CSS selector against "tree". Trailing key/value pairs can be used to declare xml namespace aliases.

  select_one
  my $result = $css->select_one('head > title');
  my $result =
    $css->select_one('svg|line', svg => 'http://www.w3.org/2000/svg');

Run CSS selector against "tree" and stop as soon as the first node matched. Trailing key/value pairs can be used to declare xml namespace aliases.

DEBUGGING
You can set the "MOJO_DOM_CSS_DEBUG" environment variable to get some advanced diagnostics information printed to "STDERR".

  MOJO_DOM_CSS_DEBUG=1

SEE ALSO
Mojolicious, Mojolicious::Guides, <https://mojolicious.org>.