I use this javascript to load a webpage that is scrolled to the area I need into an . But whenever the given iframe loads, the viewport instantly
There is nothing you can do about this. The problem is in the way you link to the source site using an anchor to move the page. Demo with a normal website:
$(document).ready(function(){
$('#asContainer').attr("src","http://www.lolwut.com");
});
http://jsfiddle.net/WGZUj/
Demo with the site you are trying to embed:
$(document).ready(function(){
$('#asContainer').attr('src','//audio-surf.com/mypage.php?u=DJDavid98#favorites_container');
});
http://jsfiddle.net/UZZ4c/
One strategy to get around this in theory would be to detect when the iframe is loaded and then move back to the original position, but this is not possible to do.