Global Variable on Google App Script

 I have trouble accessed it within function,

 so I pass it to every function,
 not so elegant solution, but it works, :) .

 In the code below, I have global variable named list.

 I have to passed as parameter on function dummy in order to edit its value or it wouldn't affected or have error message or undefined (I experienced both, :) )

function listFilesNFolders(form) {
  var list = [];
  list.push(['tadaa...<br>']);
  list.push(['heheh...']);
  var row = [];
  row.push('<br> Hello World!!! ');
  list.push(row);
  
  var home = DriveApp.getFolderById('0BxZS62a5NdNYUGxySmp2QW41OUU'); 
  
  dummy('<br> test',list);
  return list;
}

function dummy(d,list){
  list.push(d);
}

The form

 <form id="myForm">
     <input type="submit" 
    value="OK"        
    onclick="
    this.value='Proses';
    google.script.run.withSuccessHandler(fileUploaded).listFilesNFolders(this.parentNode);
    return false;
 "
                    >
 </form>

.