How to create a folder if it doesn't exist?

Question

I\'m trying to create a folder if it doesn\'t exist, but the code creates a new folder every time I run it. I don´t know if my code is right.

Here is my code:

Answer 1

Google has changed its scripting. I know this is an old post but this is the best current answer I could come up with:

function getFolder(parent_folder,folder_name){
  var folders = parent_folder.getFolders();     
  while (folders.hasNext()) {
    var folder = folders.next();
    if(folder_name == folder.getName()) {         
      return folder;
    }
  }
  return false;
}

var parent_folder = DriveApp.getFolderById(//id\\);
var folderName = getFolders(parent_folder,name);
if (folderName === false){
  folderName =  outputfolderId.createFolder(name);
}

Hope this helps someone else!