Duplicate spreadsheet file and change its name to the date when it was duplicated
<pre><code>function saveAsSpreadsheet(){
  var sheet = SpreadsheetApp.getActiveSpreadsheet();  
  var destFolder = DriveApp.getFolderById("xxxxxxxxxxxxxxxxx"); 
  DriveApp.getFileById(sheet.getId()).makeCopy("desired file name", destFolder);
}
</code></pre>

<p>How to make a the "desired file name" to be the date which the script is run (weekly basis)?</p>