php|architect's Guide to Web Scraping with PHP - Wind Business ...

134 ” CSS Selector Libraries
N o t e when reading this table that CSS selectors begin set indices at 0 whereas XPath
begins them at 1.
Content F i l t e r s
Where basic filters are based mainly on the type of node or its position in the result
set, content filters are based on node value or surrounding hierarchical structure.
• a:contains(“About Us”); selects all a nodes where the node value contains the
substring “About Us”.
• img:empty selects all img nodes that contain no child nodes (including text
nodes).
• li:has(a:contains(“About Us”)) selects all li nodes that contain an a node
with the substring “About Us” in its node value.
• li:parent selects all li nodes that contain child nodes (including text nodes).
Selector CSS XPath
nodes containing text a:contains(“About //a[contains(text(),
Us”)
“About Us”)]
nodes without
img:empty
//img[not(node())]
children
nodes containing a li:has(a:contains //li//a[contains(
selector match
(“About Us”)) text(), “About Us”)]
nodes with children li:parent //li[node()]
Attribute F i l t e r s
Filters up to this point have been specific to element nodes, but they also exist for
attribute nodes. Attribute filters are surrounded by square brackets in both CSS and
XPath, but differ in that CSS uses mostly operators for conditions while XPath uses
mostly functions. U n l i k eother filters described in this chapter, support for attribute
filters is fairly universal between different libraries.