JavaScript: Return anchor tag after string is matched

Question 1

If you want an attribute from the anchors, then it's easier to loop through the "a" tags instead of the paragraph nodes. You can use jQuery's "prev()" method to access the preceding "p" and check that its text matches your regex. http://jsfiddle.net/V86t6/13/

function myFunction(){
  var mtch = new RegExp(/Regular Edition of 325/);
  $('a').each(function () {
    if($(this).prev().find("strong").text().match(mtch)) {
      document.getElementById("demo").innerHTML=$(this).attr("href")
    }
  });
}

Note that this code will break if the html changes. Consider wrapping each label/link in a div and iterating over the containers rather than traversing using prev/next/closest, etc.

Since a pure JS version was called for (http://jsfiddle.net/V86t6/15/):

function myFunction(){
  var mtch = /Regular Edition of 325/;
  Array.prototype.forEach.call(
    document.querySelectorAll('p strong'),
    function(strong) {
      if(strong.innerHTML.match(mtch))
        document.getElementById("demo").innerHTML = strong.parentNode.nextElementSibling.href;
    }
  );
}

Question 2

You can use .filter to get the p element via the matched text:

function myFunction(){
    parseIt = $("p").find("strong");
    matchIt();
}
function matchIt(){
    resIt = parseIt.filter(function () {
        return $(this).text().match(/Regular Edition of 325/);
    });
    document.getElementById("demo").innerHTML= resIt.parent().next().text();
}

http://jsfiddle.net/V86t6/7/

Side note: don't communicate between functions via global variables. Each function should just be using its own local variables or closed-over variables.

Question 3

You can simplify this a lot by doing something like this:

function myFunction() {
    parseIt = $("p strong").filter(function () {
        return this.innerText.match(/Regular Edition of 325/);
    });
    var anchor = parseIt.parent().next("a");
}

http://jsfiddle.net/V86t6/9/

Question 4

I used this:

$('button').click(function() {
    $('p.search').each(function() {
        if(this.innerHTML.match(/Regular Edition of 325/)) {
            var $link = $(this).next('a');
            $('#demo').text($link.text());
            console.log($link);
        }
    });
});

On button click, it loops through every element you want to search. If the elements contents match the regex, then we find the next link. After this, you can do anything with the link.

JSFiddle

UPDATE:

Here is a pure-JS version. Note, that this is only compatible with IE 9+ because of my use of document.getElementsByClassName().

document.getElementById('trigger').addEventListener('click', function() {
    var paragraphs = document.getElementsByClassName('search');
    for(var i = 0; i < paragraphs.length; i++) {
        var paragraph = paragraphs[i];
        if(paragraph.innerHTML.match(/Regular Edition of 325/)) {
            var link = paragraph.nextSibling;
            while(link) {
                if(link.tagName === 'A') {
                    document.getElementById('demo').innerHTML = link.innerHTML;
                    console.log(link);

                    break;
                }

                link = link.nextSibling;
            }
        }
    }
});

JSFiddle