fortune_server.js

var fortunes = [
  "Have a nice day",
  "You look really good today",
  "It's your birthday!",
  "Never play leapfrog with a unicorn"
];

var net = require('net');
var server = net.createServer(function(connection){
  connection.write("Enter the number of fortunes you want: ");
  connection.on('data', function(data){
    var num_fortunes = parseInt(data, 10);
    if(isNaN(num_fortunes)) {
      connection.write("That's not a number, silly.")
      connection.end();
    } else if(num_fortunes > 4) {
      connection.write("You're too greedy. Ask for fewer fortunes next time.");
      connection.end();
    } else {
      for(var i = 0; i < num_fortunes; i += 1) {
        connection.write(fortunes[i] + "\n");
      }
      connection.end();
    }
    connection.on('error', function(){});
  })
});

server.listen(1234);

for(var i = 0; i < num_fortunes; i += 1) {
var fortune = fortunes[Math.floor(Math.random() * fortunes.length)];
connection.write(fortune.toString() + "\n");

gives a random number output for the fortune

if(isNaN(num_fortunes)) {
  connection.write("That's not a number, silly." + "\n");
  connection.end();
} else if(num_fortunes > 4) {
  connection.write("You're too greedy. Ask for fewer fortunes next time." + "\n");
  connection.end();
} else if(num_fortunes < 1) {
  connection.write("You need to ask for more than 0." + "\n");
  connection.end();

++

added one more condition, if the number is less than 1 and also added newline characters for the output