Paul Irish

// jQuery doOnce plugin
jQuery.fn.doOnce = function(func){ 
    this.length && func.apply(this); 
    return this; 
}

// example usage of doOnce()
$('div.toGrow')
  .doOnce(function(){
    alert('before color swap');
  })
  .css({ backgroundColor: 'red'})
  .find('h2')
    .text('And now we\'re red')
    .end() // go back to the div.toGrow
  .animate({ height: '+=50px'},'normal','swing',function(){
    $(this)  // callback when animations complete
      .find('h2')
        .text('And now we\'re taller')
        .doOnce(function(){
          alert('animation done');
        });
  });