I've found a jquery code that fits my interest. My problem is I want this jquery code to be converted to native javascript. Answers appreciated

Question

• This is the source: http://jsfiddle.net/telefonica/L2f7F/4/

  $(function() { var pressed = false; var start = undefined; var startX, startWidth;

    $("table th").mousedown(function(e) {
        start = $(this);
        pressed = true;
        startX = e.pageX;
        startWidth = $(this).width();
        $(start).addClass("resizing");
        $(start).addClass("noSelect");
    });
  
    $(document).mousemove(function(e) {
        if(pressed) {
            $(start).width(startWidth+(e.pageX-startX));
        }
    });
  
    $(document).mouseup(function() {
        if(pressed) {
            $(start).removeClass('resizing');
            $(start).removeClass('noSelect');
            pressed = false;
        }
    });
  

  });