/**
 * Polyfill from <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toISOString>.
 */
module.exports = (function() {
  var pad = function pad(n) { return (n < 10 ? '0' : '') + n; };

  return typeof Date.prototype.toISOString === 'function' ?
    function _toISOString(d) {
      return d.toISOString();
    } :
    function _toISOString(d) {
      return (
        d.getUTCFullYear() + '-' +
        pad(d.getUTCMonth() + 1) + '-' +
        pad(d.getUTCDate()) + 'T' +
        pad(d.getUTCHours()) + ':' +
        pad(d.getUTCMinutes()) + ':' +
        pad(d.getUTCSeconds()) + '.' +
        (d.getUTCMilliseconds() / 1000).toFixed(3).slice(2, 5) + 'Z'
      );
    };
}());