For use in Firefox's PDF viewer. Dumps subsection titles and page numbers for a given PDF section. Used simply in the browser console.

dump_firefox_pdf_section.js

chapter = document.getElementById("heretakeme"); // choose element somehow

chapterText = chapter.querySelector('a').innerText;
chapterLink = chapter.querySelector('a').href;
chapterPage = parseInt(decodeURI(chapterLink).split("#[")[1]) + 1;

chapterDump = "";

chapterDump += "Introduction" + "\t" + chapterPage + "\n";

sections = chapter.children[2].children;

for (var i = 0; i < sections.length; i++) {
	let section = sections[i];
	let sectionText = section.querySelector('a').innerText;
	let sectionLink = section.querySelector('a').href;
	let sectionPage = parseInt(decodeURI(sectionLink).split("#[")[1]) + 1;
	
	chapterDump += sectionText + "\t" + sectionPage + "\n";
}

console.log(chapterDump);