es.date.to-json.js

'use strict';
var $ = require('../internals/export');
var fails = require('../internals/fails');
var toObject = require('../internals/to-object');
var toPrimitive = require('../internals/to-primitive');

var FORCED = fails(function () {
  return new Date(NaN).toJSON() !== null
    || Date.prototype.toJSON.call({ toISOString: function () { return 1; } }) !== 1;
});

// `Date.prototype.toJSON` method
// https://tc39.github.io/ecma262/#sec-date.prototype.tojson
$({ target: 'Date', proto: true, forced: FORCED }, {
  // eslint-disable-next-line no-unused-vars
  toJSON: function toJSON(key) {
    var O = toObject(this);
    var pv = toPrimitive(O);
    return typeof pv == 'number' && !isFinite(pv) ? null : O.toISOString();
  }
});