// obtiene de que URL viene la peticion
var sc_url = "" + document.location;

// refactorizamos url
var re1 = new RegExp("^https://", "");
var re2 = new RegExp("^http://", "");
var re3 = new RegExp("^www\.", "");
var re4 = new RegExp("\\?.*", ""); // parametros
var re5 = new RegExp("/$", ""); // barra del final

sc_url = sc_url.toLowerCase();
var sc_url = sc_url.replace(re1, "");
var sc_url = sc_url.replace(re2, "");
var sc_url = sc_url.replace(re3, "");
var sc_url = sc_url.replace(re4, "");
var sc_url = sc_url.replace(re5, "");

// hace la peticion
document.writeln("<img src=\"http://www.top100coches.com/php/cuentaVisita.php?reqWebId=" + id + "&u=" + sc_url + "\">");