Twilio's requirement is not defined error

I try to use Twilio in a file .js , in some labels <script> I have:

var twilio = require('twilio');
var client = new twilio.RestClient('######', '#####');
client.sms.messages.create({
    to:'#######',
    from:'#######',
    body:'Bienvenido Sr(a): '+$('input[name=nombre]').val()+''
}, function(error, message) {
if (!error) {
    console.log('Mensaje enviado');
    console.log(message.sid);

    console.log('Message sent on:');
    console.log(message.dateCreated);
} else {
    console.log('Mensaje no enviado');
    console.log(error);
  }
});

The code works perfectly in a .js but when I include it somewhere else in a few tags script obviously, it does not work, it shows me the following error:

  

ReferenceError: require is not defined ...

Thanks for the attention.