$("button").on("click", function() {
  
  // cache textarea as we need it more than once
  var textarea = $("textarea"),
      
      // save old value as we need to clear it
      val = textarea.val();
  
  // focus textarea, clear value, re-apply
  textarea
    .focus()
    .val("")
    .val(val);
});

This demo does that but also applies a little bit of UX. If the textarea's current value doesn't end in a space, add one. Just so you can click-and-keep-typing as you might.

Check out this Pen!

You could make it a plugin as well:

$.fn.focusToEnd = function() {
   return this.each(function() {
       var v = $(this).val();
       $(this).focus().val("").val(v);
   });
};

(function() {
  var resizeTimer;
  
  // Assuming we have jQuery present
  $( window ).on( "resize", function() {
    
    // Use resizeTimer to throttle the resize handler
    clearTimeout( resizeTimer );
    resizeTimer = setTimeout(function() {

     /* Send the event to Google Analytics
      *
      * https://developers.google.com/analytics/devguides/collection/gajs/methods/gaJSApiEventTracking
      * _trackEvent(category, action, opt_label, opt_value, opt_noninteraction)   
      */
      var $window = $( window );
      _gaq.push( [ "_trackEvent", "User Actions", "Browser Resize", $window.width() + " x " + $window.height() ] );
    }, 1000);
  });
})();

Note how easy it is to track events in Google Analytics. That can be used for just about anything.

var input = $("#control");

function something_happens() {
    input.replaceWith(input.val('').clone(true));
};

(function($) {
    $.fn.drags = function(opt) {

        opt = $.extend({handle:"",cursor:"move"}, opt);

        if(opt.handle === "") {
            var $el = this;
        } else {
            var $el = this.find(opt.handle);
        }

        return $el.css('cursor', opt.cursor).on("mousedown", function(e) {
            if(opt.handle === "") {
                var $drag = $(this).addClass('draggable');
            } else {
                var $drag = $(this).addClass('active-handle').parent().addClass('draggable');
            }
            var z_idx = $drag.css('z-index'),
                drg_h = $drag.outerHeight(),
                drg_w = $drag.outerWidth(),
                pos_y = $drag.offset().top + drg_h - e.pageY,
                pos_x = $drag.offset().left + drg_w - e.pageX;
            $drag.css('z-index', 1000).parents().on("mousemove", function(e) {
                $('.draggable').offset({
                    top:e.pageY + pos_y - drg_h,
                    left:e.pageX + pos_x - drg_w
                }).on("mouseup", function() {
                    $(this).removeClass('draggable').css('z-index', z_idx);
                });
            });
            e.preventDefault(); // disable selection
        }).on("mouseup", function() {
            if(opt.handle === "") {
                $(this).removeClass('draggable');
            } else {
                $(this).removeClass('active-handle').parent().removeClass('draggable');
            }
        });

    }
})(jQuery);

Usage

$('div').drags();

Demo

Let's say you have navigation like this:

<nav>
	<ul>
		<li><a href="/">Home</a></li>
		<li><a href="/about/">About</a></li>
		<li><a href="/clients/">Clients</a></li>
		<li><a href="/contact/">Contact Us</a></li>
	</ul>
</nav>	

And you are at the URL:

http://yoursite.com/about/team/

And you want the About link to get a class of "active" so you can visually indicate it's the active navigation.

$(function() {
  $('nav a[href^="/' + location.pathname.split("/")[1] + '"]').addClass('active');
});

Essentially that will match links in the nav who's href attribute begins with "/about" (or whatever the secondary directory happens to be).