[etc]

function trimss (str:String,symbol:String):String {
	str = new String (str);
        symbol = symbol.length ? symbol : ' ';
	var sx:Number = 0;
	var ex:Number = str.length;
	while (str.charAt (sx) == symbol) {
		sx++;
	}
	while (str.charAt (ex - 1) == symbol) {
		ex--;
	}
	str = str.substring (sx, ex);
	return str;
}

Уверен?