functionfoundry/fn/parsedate.js

Pure function JavaScript library

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = parsedate;

var _constants = require('./constants');

var _error = require('./error');

var _error2 = _interopRequireDefault(_error);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

// PARSEDATE converts a value into a Date object.
// Copyright 2015 JC Fisher

function parsedate(val) {

  /* *******************
  Extracted from Social Calc
   convert_date_julian_to_gregorian(juliandate)
   ymd->{}
  .year
  .month
  .day
   From: http://aa.usno.navy.mil/faq/docs/JD_Formula.html
  Uses: Fliegel, H. F. and van Flandern, T. C. (1968). Communications of the ACM, Vol. 11, No. 10 (October, 1968).
  Translated from the FORTRAN
   ************************* */
  function convert_date_julian_to_gregorian(juliandate) {

    var L, N, I, J, K;

    L = juliandate + 68569;
    N = Math.floor(4 * L / 146097);
    L = L - Math.floor((146097 * N + 3) / 4);
    I = Math.floor(4000 * (L + 1) / 1461001);
    L = L - Math.floor(1461 * I / 4) + 31;
    J = Math.floor(80 * L / 2447);
    K = L - Math.floor(2447 * J / 80);
    L = Math.floor(J / 11);
    J = J + 2 - 12 * L;
    I = 100 * (N - 49) + I + L;

    return new Date(I, J - 1, K);
  }

  if (val instanceof Error) {
    return val;
  } else if (typeof val === 'number') {
    // val is assumed to be serial number.
    return convert_date_julian_to_gregorian(Math.floor(val + _constants.JulianOffset));
  } else if (typeof val === 'string') {
    var timestamp = Date.parse(val);
    if (Number.isNaN(timestamp)) {
      return _error2.default.value;
    }
    return new Date(timestamp);
  }

  return _error2.default.value;
}
module.exports = exports['default'];