functionfoundry/fn/isoweeknum.js

Pure function JavaScript library

'use strict';

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

var _parsedate = require('./parsedate');

var _parsedate2 = _interopRequireDefault(_parsedate);

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

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

// Copyright 2015 JC Fisher

function isoweeknum(date) {
    date = (0, _parsedate2.default)(date);

    if (date instanceof Error) {
        return date;
    }

    date.setHours(0, 0, 0);
    date.setDate(date.getDate() + 4 - (date.getDay() || 7));
    var yearStart = new Date(date.getFullYear(), 0, 1);
    return Math.ceil(((date - yearStart) / _constants.MilliSecondsInDay + 1) / 7);
};
module.exports = exports['default'];