javascript waiting php to complete function and refresh page

Question

I have following case:

1. I have drop down menu from where I select currency for a website and trigger javascript function changecurrency() using onchange event

Answer 1

Pass your callback function as the second parameter:

jQuery('#div_session_write').load('update_currency.php?val=' + x, _callback);

That way, it is automatically called by jQuery when the request finishes loading. See the documentation for more info: http://api.jquery.com/load/