jQuery provides a method $.get
which can capture the data from a URL. So to “read” the html/text document, it needs to be accessible through a URL. Once you fetch the HTML contents you should just be able to wrap that markup as a jQuery wrapped set and search it as normal.
Untested, but the general gist of it…
var HTML_FILE_URL = '/whatever/html/file.html';
$(document).ready(function() {
$.get(HTML_FILE_URL, function(data) {
var fileDom = $(data);
fileDom.find('h2').each(function() {
alert($(this).text());
});
});
});