Fbnames.js

javascript:
var y = document.getElementsByClassName('_zs fwb');
var flag = 0;
var p;
p = window.prompt('Enter no of names required ', 10);

  function moveWin()
{
  window.scroll(0, document.body.scrollHeight);
  y = document.getElementsByClassName('_zs fwb');
  if (y.length > p)
  {
    clearTimeout(stopScroll);
    flag = 1;
  }
  else
  var stopScroll = setTimeout('moveWin();', 1000);
  if (flag == 1)
  {
    y = document.getElementsByClassName('_zs fwb');
    var final = [
      [' USERNAME ',
      ' ID ']
    ];
    var names = [
    ];
    var ids = [
    ];
    var csvRows = [
    ];
    for (var i = 0; i < p; i++)
    {
      var name = y[i].textContent;
      names.push(name);
      var url = y[i].getElementsByTagName('a') [0].href;
      var id = url.slice(25, url.indexOf('?'));
      ids.push(id);
      final.push([name,
      id]);
    }
    for (var i = 0 ; i < final.length ; ++i)
    {
      csvRows.push(final[i].join(','));
    }
    var csvString = csvRows.join('%0A');
    var a = document.createElement('a');
    a.href = 'data:attachment/csv,' + csvString;
    a.target = '_blank';
    a.download = 'FBnames.csv';
    if (csvRows.length > 1)
    {
      document.body.appendChild(a);
      a.click();
    }
  }
}
moveWin();
void (0);