How to run server.js written in js with Node.js

i have a file with nodejs language which i found in the internet, i want to run it, but i don't know how to run it. i tryed to run with cmd command: node server.js but it not work.

please, show me how to run it.

file server.js

var port = process.env.PORT || 3000;
server   = require('http').createServer(),
io       = require('socket.io').listen(server),

users = {}, socks = {};

function Uid() { this.id = ++Uid.lastid; }

Uid.lastid = 0;

//Handle users
io.sockets.on('connection', function (socket) {

        // Event received by new user
        socket.on('join', function (recv) {

                if (!recv.user) {
                        socket.emit('custom_error', { message: 'User not found or invalid' });
                        return;
                }

                // The user already exists
                if (users[recv.user]) {
                        socket.emit('custom_error', { message: 'The user '+ recv.user +' already exists' });
                        return;
                }

                // If there is users online, send the list of them
                if (Object.keys(users).length > 0)
                        socket.emit('chat', JSON.stringify( { 'action': 'usrlist', 'user': users } ));

                // Set new uid
                uid = new Uid();
                socket.user = recv.user;

                // Add the new data user
                users[socket.user] = {'uid': Uid.lastid, 'user': socket.user, 'name': recv.name, 'status': 'online'}
                socks[socket.user] = {'socket': socket}

                // Send new user is connected to everyone
                socket.broadcast.emit('chat', JSON.stringify( {'action': 'newuser', 'user': users[socket.user]} ));
        });

        // Event received when user want change his status
        socket.on('user_status', function (recv) {
                users[socket.user].status = recv.status;
                socket.broadcast.emit('chat', JSON.stringify( {'action': 'user_status', 'user': users[socket.user]} ));
        });

        // Event received when user is typing
        socket.on('user_typing', function (recv) {
                var id  = socks[recv.user].socket.id;
                io.sockets.socket(id).emit('chat', JSON.stringify( {'action': 'user_typing', 'data': users[socket.user]} ));
        });

        // Event received when user send message to another
        socket.on('message', function (recv) {
                var id  = socks[recv.user].socket.id;
                var msg = {'msg': recv.msg, 'user': users[socket.user]};
                io.sockets.socket(id).emit('chat', JSON.stringify( {'action': 'message', 'data': msg} ));
        });

        // Event received when user has disconnected
        socket.on('disconnect', function () {
                socket.broadcast.emit('chat', JSON.stringify( {'action': 'disconnect', 'user': users[socket.user]} ));
                //socket.broadcast.emit('chat', JSON.stringify( {'action': 'offline', 'user': users[socket.user]} ));
                delete users[socket.user];
                delete socks[socket.user];
        });
});

//Listen to the server port
server.listen(port, function () {
  var addr = server.address();
  console.log('jquery-chat server listening and ready');
});