@head.js/analytics.js-new-date/lib/index.js

Creates a new Date, but accepts a few more input types than normal.

"use strict";

var isodate = require("@segment/isodate");
var milliseconds = require("./milliseconds");
var seconds = require("./seconds");

var objProto = Object.prototype;
var toStr = objProto.toString;

function isDate(value) {
  return toStr.call(value) === "[object Date]";
}

function isNumber(value) {
  return toStr.call(value) === "[object Number]";
}

/**
 * Returns a new Javascript Date object, allowing a variety of extra input types
 * over the native Date constructor.
 *
 * @param {Date|string|number} val
 */
module.exports = function newDate(val) {
  if (isDate(val)) return val;
  if (isNumber(val)) return new Date(toMs(val));

  // date strings
  if (isodate.is(val)) {
    return isodate.parse(val);
  }
  if (milliseconds.is(val)) {
    return milliseconds.parse(val);
  }
  if (seconds.is(val)) {
    return seconds.parse(val);
  }

  // fallback to Date.parse
  return new Date(val);
};

/**
 * If the number passed val is seconds from the epoch, turn it into milliseconds.
 * Milliseconds would be greater than 31557600000 (December 31, 1970).
 *
 * @param {number} num
 */
function toMs(num) {
  if (num < 31557600000) return num * 1000;
  return num;
}