How to check if current folder in document library has child items via JavaScript client object model?

Question

I have a custom button on ribbon, which performs some action with current folder (download folder content as zip package). I want to disable this button in case if current folder doesn't contain any items - neither files nor subfolders. Could you please help me with JavaScript code for "EnabledScript" property of "CommandUIHandler"?

Answer 1

You could extract the current folder location from the RootFolder parameter of the URL of the current displayed view. Then load the folder like this:

  <script>
    function GetItemCount()
    {
      // extract folder URL from request parameter RootFolder
      var folderUrl = ...;

      var ctx = new SP.ClientContext();
      var web = ctx.get_web();
      ctx.load(web);
      var folder = web.getFolderByServerRelativeUrl(folderUrl);
      ctx.load(folder);
      ctx.executeQueryAsync(function(s, a){ alert(folder.get_itemCount()) });    
    }
  </script>
  <a href='javascript:GetItemCount();'>Get item count</a>