How to extend the Javascript Date object?

Question

I\'m trying to subclass/extend the native Date object, without modifying the native object itself.

I\'ve tried this:

    var util = require(\'util\')         


        

Answer 1

Based on answer by @sstur

We can use Function.prototype.bind() to construct the Date object dynamically with the passed in arguments.

See: Mozilla Developer Network: bind() method

function XDate() {
  var x = new (Function.prototype.bind.apply(Date, [Date].concat(Array.prototype.slice.call(arguments))))
  x.__proto__ = XDate.prototype;
  return x;
}

XDate.prototype.__proto__ = Date.prototype;

XDate.prototype.foo = function() {
  return 'bar';
};

Verification:

var date = new XDate(2015, 5, 18)
console.log(date instanceof Date) //true
console.log(date instanceof XDate) //true
console.log(Object.prototype.toString.call(date)) //[object Date]
console.log(date.foo()) //bar
console.log('' + date) // Thu Jun 18 2015 00:00:00 GMT-0500 (CDT)