去掉url前缀

function removeUrlPrefix(a) {
  a = a
    .replace(/：/g, ":")
    .replace(/．/g, ".")
    .replace(/／/g, "/");
  while (
    trim(a)
      .toLowerCase()
      .indexOf("http://") == 0
  ) {
    a = trim(a.replace(/http:\/\//i, ""));
  }
  return a;
}