_getDirPathOfUrl = function(url) {
    var dir;
    if (typeof url === "string" && url) {
      dir = url.split("#")[0].split("?")[0];
      dir = url.slice(0, url.lastIndexOf("/") + 1);
    }
    return dir;
  }
Get the URL path's parent directory.

@returns String or `undefined`
@private