old_contents: (function () {
    // Obtain ALL anchors on the page.
    var links = document.links,
  
    // The previous/next urls if they exist.
        prev = findHref(/(prev|back)/i),
        next = findHref(/(next|forward)/i),
  
    // The first/last urls if they exist.
        first = findHref(/(first|start|oldest)/i),
        last = findHref(/(last|end|newest|latest)/i);
  
    /**
     * Find the href for a given name.
     * @param {String} name - The name of the anchor to search for.
     * @return {String} The href for a given tag, otherwise an empty string.
     */
    function findHref(name) {
      var anchor,
        index = 0;
      for (; index < links.length; index++) {
        // The complete anchor HTML element (<a>).
        anchor = links[index];
        // Does the name exist in the anchor?
        if (isNameInAnchor(name, anchor.className) ||
            isNameInAnchor(name, anchor.rel) ||
            isNameInAnchor(name, anchor.text))
        {
          return anchor.href;
        }
      }
    }
  
    /**
     * Does the word exist in a given element?
     * @param {String} name - The name to search for.
     * @param {String} element - The element to search in.
     * @return {Boolean} True if the name exists in the element, otherwise false.
     */
    function isNameInAnchor(name, element) {
      return element !== void 0 && element.search(name) >= 0;
    }
  
    // Go to the next/previous pages using the arrow keys.
    document.addEventListener('keydown', function(event) {
      if (event.keyCode !== 37 && event.keyCode !== 39) {
        return;
      }
  
      var key = (event.shiftKey && "shift_" || "") + event.keyCode,
        navTo = {
          "37": prev,
          "39": next,
          "shift_37": first,
          "shift_39": last
        }[key];
  
      if (navTo) {
        window.location = navTo;
      }
    });
  })();
  
new_contents: (function () {
    'use strict';
    // Obtain ALL anchors on the page.
    var links = document.links,
  
    // The previous/next urls if they exist.
        prev = findHref(/(prev|back)/i),
        next = findHref(/(next|forward)/i),
  
    // The first/last urls if they exist.
        first = findHref(/(first|start|oldest)/i),
        last = findHref(/(last|end|newest|latest)/i);
  
    /**
     * Find the href for a given name.
     * @param {String} name - The name of the anchor to search for.
     * @return {String} The href for a given tag, otherwise an empty string.
     */
    function findHref(name) {
      var anchor,
        index = 0;
      for (; index < links.length; index++) {
        // The complete anchor HTML element (<a>).
        anchor = links[index];
        // Does the name exist in the anchor?
        if (isNameInAnchor(name, anchor.className) ||
            isNameInAnchor(name, anchor.rel) ||
            isNameInAnchor(name, anchor.text))
        {
          return anchor.href;
        }
      }
    }
  
    /**
     * Does the word exist in a given element?
     * @param {String} name - The name to search for.
     * @param {String} element - The element to search in.
     * @return {Boolean} True if the name exists in the element, otherwise false.
     */
    function isNameInAnchor(name, element) {
      return element !== void 0 && element.search(name) >= 0;
    }
  
    // Go to the next/previous pages using the arrow keys.
    document.addEventListener('keydown', function(event) {
      if (event.keyCode !== 37 && event.keyCode !== 39) {
        return;
      }
  
      var key = (event.shiftKey && "shift_" || "") + event.keyCode,
        navTo = {
          "37": prev,
          "39": next,
          "shift_37": first,
          "shift_39": last
        }[key];
  
      if (navTo) {
        window.location = navTo;
      }
    });
  })();
  
subject: use strict mode