In Tritium, how can I select the previous/next element? - xpath

Question

I'm using the Moovweb SDK to transform a website, and I have a lot of pages with content that matches this format. There is an <h2> that begins a section, and that section has a random number of <p> elements.
Since these elements have no attributes, I can’t select by class or id. I want to select the first and last <p> in each section. I don’t want to have to manually select like $('./p[1]') , $('./p[4]') etc... Is there a way to select the elements before and after each <h2>?
<div>
<h2>This is a heading</h2>
<p>Here is some content</p>
<p>Meh</p>
<p>Here's another paragraph</p>
<p>Important sentence because it's the last one</p>
<h2>Here's a subheading</h2>
<p>Topic sentence</p>
<p>Bleh bleh bleh</p>
<p>Hurray, this fragment.</p>
<p>May the Force be with you</p>
<p>Moovweb rocks!</p>
<h2>New heading</h2>
<p>More awesome content here</p>
<p>Why is there so much stuff?</p>
<h2>The end</h2>
<p>Or is it?</p>
</div>

Answer 1

You can use the preceding-sibling and following-sibling selectors in XPath to do this!
The code would look something like this:
$("./div"){
$("./h2") {
$("following-sibling::p[1]") { # first p after h2
# do stuff
}
$("preceding-sibling::p[1]") { # first p before h2
# do stuff
}
}
}
See this example I created in the Tritium Tester: http://tester.tritium.io/dc25a419ac15fad70fba6fd3d3a9b512cb8430e8