Date.prototype.toJSON

Date.prototype.toJSON.js

function f(n) {
        return n < 10 ? '0' + n : n;
}

Date.prototype.toJSON = function () {
  return isFinite(this.valueOf())
      ? this.getUTCFullYear()     + '-' +
          f(this.getUTCMonth() + 1) + '-' +
          f(this.getUTCDate())      + 'T' +
          f(this.getUTCHours())     + ':' +
          f(this.getUTCMinutes())   + ':' +
          f(this.getUTCSeconds())   + 'Z'
      : null;
};