如何从下一个Js URL中删除子文件夹名称？

function removeSubfolderFromUrl(url) {
  var urlArray = url.split('/');
  urlArray.pop();
  var newUrl = urlArray.join('/');
  return newUrl;
}

var url = 'http://www.example.com/folder/subfolder/file.js';
var newUrl = removeSubfolderFromUrl(url);
console.log(newUrl);