var express = require('express');
var methods = require('../methods/method');
var router = express.Router();

/* GET home page. */
router.get('/', function(req, res, next) {
res.render('page1.html', { title: 'Welcome to My World'} );
});
/* GET POST data form entry */
router.post('/action', function(req, res) {
methods.process(req, res);
});
module.exports = router;

<script src="/javascripts/socket.io.js"></script>
<script>
var sock  = io.connect('http://xx.xx.xxx.xx:xxxx', {'timeout' : 1000 , 'reconnection' : false, 'forceNew' : true});
sock.on('start', function (data) {
        console.log('Start of arriving data');
});
sock.on('message', function (data) {
        console.log('Data arrived .. ');
        //code to render it in my current Web Page
});
sock.on('end', function (data) {
        console.log('my connection closed');
        sock.close();
        sock.disconnect();
        sock.destroy();
});
sock.on( 'disconnect', function() {
        sock.close();
        sock.disconnect();
        sock.destroy();
    console.log('my connection dropped');
} );
sock.on( 'reconnect', function() {
        sock.close();
        sock.disconnect();
        sock.destroy();
    console.log('my connection has been restored!');
} );
</script>

exports.process = function(req, resp) {
    resp.render('page2.html', { title: 'Welcome to My World' });
    exec_script(resp);
};

exec_script = function(resp) {
      sock.on('connection', function (client) {
      client.emit('start');
      console.log('Connection Established');
      client.on('disconnect', function () {
          console.log('disconnected');
      });
   var pyshell = new PythonShell('./test.py', options ={ mode: 'text', pythonOptions: ['-u'] });
   pyshell.stdout.on('data', function(data) {
    client.emit('message', data);
    console.log(data);
  });
  pyshell.end(function(err) {
    if (err) throw err;
    console.log('End Script');
    client.emit('end', 'end');
    resp.end();
});
});
};

First Execution:

Connection Established
<output data of Python test.py for first execution>
End Script
disconnected

Second Execution

Connection Established
Connection Established
<output data of Python test.py for first execution>
<output data of Python test.py for second execution>
End Script
End Script
disconnected
disconnected

exports.process = function(req, resp) {
    resp.render('page2.html', { title: 'Welcome to My World' });
    var state = 'start'; // declared a new variable and initialized it as 'start'
    exec_script(resp, state);
};

exec_script = function(resp, state) {
      sock.on('connection', function (client) {
      console.log('State While Entering: ' +  state);
      if (state === 'start')
      {
      console.log('State Inside if: ' +  state);
      state = 'done';
      console.log('State After Changed: ' +  state);
      client.emit('start');
      console.log('Connection Established');
      client.on('disconnect', function () {
          console.log('disconnected');
      });
   var pyshell = new PythonShell('./test.py', options ={ mode: 'text', pythonOptions: ['-u'] });
   pyshell.stdout.on('data', function(data) {
    client.emit('message', data);
    console.log(data);
  });
  pyshell.end(function(err) {
    if (err) throw err;
    console.log('End Script');
    client.emit('end', 'end');
    resp.end();
});
}
});

exec_script = function(resp, state) {
sock.on('connection', function (client) {
console.log('State While Entering: ' +  state);
if (state === 'start')
{
console.log('State Inside if: ' +  state);
state = 'done';
console.log('State After Changed: ' +  state);
   var pyshell = new PythonShell('./test.py', options ={ mode: 'text', pythonOptions: ['-u'] });
   pyshell.stdout.on('data', function(data) {
    client.emit('message', data);
    console.log(data);
  });
.............
}
});

First Execution:

State While Entering: start
State Inside if: start
State After Changed: done
Connection Established
<output data of Python test.py for first execution>
End Script
disconnected

Second Execution:

State While Entering: done
State While Entering: done
State While Entering: start
State Inside if: start
State After Changed: done
Connection Established
<output data of Python test.py for second execution>
End Script
disconnected