Node.js fs read async text file and split by lines

var fs=require('fs'); /*Llamamos a la libreria fs*/

fs.readFile('/home/hector/node/archprog3.txt','utf8',function callback(err,data){
  var str=data.toString();  
  var splt=str.split("\n");
  console.log(splt.length)/*from   w w w  . j a  v a  2  s  .  c om*/
})