Simulating Interfaces in Javascript

Anybody could tell me if this way of simulating interfaces in javascript is correct?

$(document).on('ready', function(){
//Simulating Interfaces in Javascript using Functions with Call
var IPayable = function(){
  this.payAmount = null;
  this.payment = function(fn){return fn(this);};
  this.paymentInform = function(fn){return fn(this);};
};

var IAlertable = function(){
  this.maxPayAmount = null;
  this.maxExceeded = function(fn){return fn(this);};
};

var User = {userName: 'Adam'};

//Assigning the Interfaces
IPayable.call(User);
IAlertable.call(User);

User.payment(function(User){ //Using the first function of IPayable
  User.payAmount = 100; //Update the amount for later use
  User.maxPayAmount = 30; //Update the maximum you cannot exceed
   User.maxExceeded(function(User){ //Using the IAlertable
    if(User.payAmount > User.maxPayAmount){
      console.log(User.userName + ' your max was exceeded ' + 
                  (User.payAmount - User.maxPayAmount + '$'));
    }else{
      console.log(User.userName + ' has made a payment of: ' + User.payAmount + '$');
      User.paymentInform(function(User){ //Using the seconf function of IPayable
          console.log('Your payment of '+ User.payAmount +'$ was made');
      });  
    }
  });
});
});

It works to me but I will great if anybody can tell me If I'm wrong.