accepting input from a pipe, nodejs

pipeaccept.js

  var data;

  process.stdin.resume();
  process.stdin.setEncoding('utf8');

  process.stdin.on('data', function(chunk) {
    data += chunk;
  });

  process.stdin.on('end', function() {
    callback(data)
  });

  setInterval(function() {
    console.error('working');
  }, 1e3);

You should change var data; to var data = ''; or else the data will be "undefinedTHE_ACTUAL_DATA"