I want to write a localStorage item to a text file and want to invoke user to store the file in a specified location. Please help me with extending the code

  var data = JSON.parse(localStorage.getItem(pid));   

  var Text2Write = ;

  for(var pr in ele)

  {

     var dat = pr + : + ele[pr] + n;

     Text2Write += dat;

  }

  // Here I want to store this Text2Write to text file and ask user to save where he wants.  

Please help me extending this code.