holyfills/lib/date/date_toJSON.js

No more "Holy Sxxt!!" when writting ES5/ES6

"use strict";
var assignProperty = require("../helpers/assignProperty");
var DatePrototype = require("../helpers/DatePrototype");
var toPrimitive = require("../helpers/toPrimitive");

module.exports = HAS_DATE_TO_JSON ? DatePrototype.toJSON : function (key) {
  // When the toJSON method is called with argument key, the following
  // steps are taken:

  // 1.  Let O be the result of calling ToObject, giving it the this
  // value as its argument.
  // 2. Let tv be toPrimitive(O, hint Number).
  var o = Object(this),
      tv = toPrimitive(o),
      toISO;
  // 3. If tv is a Number and is not finite, return null.
  if (typeof tv === "number" && !isFinite(tv)) {
    return null;
  }
  // 4. Let toISO be the result of calling the [[Get]] internal method of
  // O with argument "toISOString".
  toISO = o.toISOString;
  // 5. If IsCallable(toISO) is false, throw a TypeError exception.
  if (typeof toISO !== "function") {
    throw new TypeError("toISOString property is not callable");
  }
  // 6. Return the result of calling the [[Call]] internal method of
  //  toISO with O as the this value and an empty argument list.
  return toISO.call(o);

  // NOTE 1 The argument is ignored.

  // NOTE 2 The toJSON function is intentionally generic; it does not
  // require that its this value be a Date object. Therefore, it can be
  // transferred to other kinds of objects for use as a method. However,
  // it does require that any such object have a toISOString method. An
  // object is free to use the argument key to filter its
  // stringification.
};

// ES5 15.9.5.44
// http://es5.github.com/#x15.9.5.44
// This function provides a String representation of a Date object for use by
// JSON.stringify (15.12.3).
assignProperty(DatePrototype, "toJSON", module.exports, !IS_DATE_TO_JSON_WORKS_AS_EXPECTED);