How to create local folders in web development

("deviceready", onDeviceReady, false);

function onDeviceReady() {
      // alert('ondeviceReady');
      //  =  || ;
      ("Document Center===========>Software ready：Set the detection file storage directory to start.");
      (, 0, function (fileSystem) {
        ("Document Center===========>Method for detecting temporary file storage directory");
        // Global variable, here is zgky        (filemanage_util.appRootDirName, {
          create: true,
          exclusive: false
        }, function (entry) {
          //The information circulated online uses fullPath. Here I get the relative directory. When using it, it will cause an error. So I changed to URL()          //This is a global variable to save the path          ("Document Center===========>The folder was created successfully,Setting relevant parameters！");
          filemanage_util.fullPath = ();
          // alert();
          ("Document Center===========>The folder was created successfully:" + filemanage_util.fullPath);
          //();
        }, function () {
          ("Document Center===========>Failed to create a folder！");
        });
        ("Document Center===========>The method of detecting temporary file directory ends!");
      }, function () {
        ("Document Center===========>Failed to create a folder");
      });
      ("Document Center===========>Software ready：Set the end of the detection file storage directory");
    };