Dynamic iframe

gistfile1.js

	function sendChatterMessage(sfdc_base_url, message_text){
		$jquery('<iframe />', {
		    name: 'chatterFrame',
		    id:   'chatterFrame',
			width: '800px',
			height: '800px',
			src: 'https://' + sfdc_base_url + '/_ui/core/chatter/ui/ChatterPage'
		}).appendTo('body');

		$jquery('#chatterFrame').load(function(){
// This line works
			$jquery('#chatterFrame').contents().find('#publishereditablearea').val(message_text);

// This line (and multiple similar, document.getElementByID, etc.) do not work, though they work correctly from js console

			window.frames["chatterFrame"].chatter.getPublisher().submit('', 'S');	
	    });

	}