With XPath, how would you search for elements that only contain another specific element? For example, what expression would result in getting all <p> tags that contain <strong> elements within them?
<p>This is some text that <strong>contains another HTML element</strong></p>
In XPath you use square brackets to filter. It is called the predicate. See I.e. this tutorial .
To select all p’s with a element strong you use
//p[strong]
If you want to find all p’s with only the element strong and no other elements, you add
//p[strong][count(*)=count(strong)]
The * stands for any element.
If, as in your example , you only interested in p’s with the strong element being the last child node you use
//p[strong[not(following-sibling::node())]]
Predicates are the way to go.
what expression would result in getting all p tags that contain elements within them?
If you only want to select p elements with direct strong children, you can use p[strong], if you're looking for any descendants, use p[descendant::strong]. In both cases the context node has to be at the level of the p elements.