I tried to use the Nicolás solution, but the conversion was never tested.
However, I found an article describing a method that worked instantly using the URL from <noscript><img src="..." /></noscript>.
Put an element on your page, for example:
<div id="fb_pixel"></div>
Then declare these CSS rules for your conversions, changing background-imagefor the URL <noscript>found in your own tracking code.
#fb_pixel { display:none; }
.fb_conversion
{
background-image: url('https://www.facebook.com/offsite_event.php?id=33333333333&value=0¤cy=USD');
}
, (, AJAX), fb_conversion <div> JavaScript. , jQuery:
$("#fb_pixel").addClass("fb_conversion");
, .