javascript - How to write a object oriented Node.js model -

i having lot of trouble writing object oriented cat class in node.js. how can write cat.js class , use in following way:

// following 10 lines of code in file "app.js" outside  // folder "model" var cat = require('./model/cat.js');  var cat1 = new cat(12, 'tom'); cat1.setage(100); console.log(cat1.getage()); // prints out 100 console  var cat2 = new cat(100, 'jerry'); console.log(cat1.equals(cat2)); // prints out false  var sameascat1 = new cat(100, 'tom'); console.log(cat1.equals(sameascat1)); // prints out true 

how fix following cat.js class have written:

 var cat = function() {     this.fields = {         age: null,         name: null     };      this.fill = function (newfields) {         for(var field in this.fields) {             if(this.fields[field] !== 'undefined') {                 this.fields[field] = newfields[field];             }         }     };      this.getage = function() {         return this.fields['age'];     };      this.getname = function() {         return this.fields['name'];     };      this.setage = function(newage) {         this.fields['age'] = newage;     };      this.equals = function(othercat) {         if (this.fields['age'] === othercat.getage() &&              this.fields['name'] === othercat.getname())  {             return true;         } else {             return false;         }     }; };  module.exports = function(newfields) {     var instance = new cat();     instance.fill(newfields);     return instance; }; 

if design object this, have done this

function cat(age, name) {       // accept name , age in constructor     this.name = name || null;     this.age  = age  || null; }  cat.prototype.getage = function() {     return this.age; }  cat.prototype.setage = function(age) {     this.age = age; }  cat.prototype.getname = function() {     return this.name; }  cat.prototype.setname = function(name) {     this.name = name; }  cat.prototype.equals = function(othercat) {     return othercat.getname() == this.getname()         && othercat.getage() == this.getage(); }  cat.prototype.fill = function(newfields) {     (var field in newfields) {         if (this.hasownproperty(field) && newfields.hasownproperty(field)) {             if (this[field] !== 'undefined') {                 this[field] = newfields[field];             }         }     } };  module.exports = cat;     // export cat function 

and can used this

var cat = require("./cat.js");  var cat1 = new cat(12, 'tom'); cat1.setage(100); console.log(cat1.getage());                 // 100  var cat2 = new cat(100, 'jerry'); console.log(cat1.equals(cat2));             // false  var sameascat1 = new cat(100, 'tom'); console.log(cat1.equals(sameascat1));       // true  var sameascat2 = new cat(); console.log(cat2.equals(sameascat2));       // false  sameascat2.fill({name: "jerry", age: 100}); console.log(cat2.equals(sameascat2));       // true