example_of_fs.watch_with_events

'use strict';
const
    fs = require('fs'),
    filename = process.argv[2];

console.log('--watching %s',filename);

var watcher=fs.watch(filename);

watcher.on('change',function(){
  console.log('--%s has changed.');
  watcher.close();
  let stream=fs.createReadStream(filename);
  stream.on('data',function(chunk){
    process.stdout.write(chunk);
  });
  stream.on('end',function(){
    stream.close();
    watcher=fs.watch(filename);
  });
  stream.on('error',function(err){
    stream.close();
    console.error('--failed to read from stream: %s', err);
  })
});