dayjs/esm/plugin/objectSupport/index.js

export default (function (o, c, dayjs) {
  var proto = c.prototype;

  var isObject = function isObject(obj) {
    return obj !== null && !(obj instanceof Date) && !(obj instanceof Array) && !proto.$utils().u(obj) && obj.constructor.name === 'Object';
  };

  var prettyUnit = function prettyUnit(u) {
    var unit = proto.$utils().p(u);
    return unit === 'date' ? 'day' : unit;
  };

  var parseDate = function parseDate(cfg) {
    var date = cfg.date,
        utc = cfg.utc;
    var $d = {};

    if (isObject(date)) {
      if (!Object.keys(date).length) {
        return new Date();
      }

      var now = utc ? dayjs.utc() : dayjs();
      Object.keys(date).forEach(function (k) {
        $d[prettyUnit(k)] = date[k];
      });
      var d = $d.day || (!$d.year && !($d.month >= 0) ? now.date() : 1);
      var y = $d.year || now.year();
      var M = $d.month >= 0 ? $d.month : !$d.year && !$d.day ? now.month() : 0; // eslint-disable-line no-nested-ternary,max-len

      var h = $d.hour || 0;
      var m = $d.minute || 0;
      var s = $d.second || 0;
      var ms = $d.millisecond || 0;

      if (utc) {
        return new Date(Date.UTC(y, M, d, h, m, s, ms));
      }

      return new Date(y, M, d, h, m, s, ms);
    }

    return date;
  };

  var oldParse = proto.parse;

  proto.parse = function (cfg) {
    cfg.date = parseDate.bind(this)(cfg);
    oldParse.bind(this)(cfg);
  };

  var oldSet = proto.set;
  var oldAdd = proto.add;
  var oldSubtract = proto.subtract;

  var callObject = function callObject(call, argument, string, offset) {
    if (offset === void 0) {
      offset = 1;
    }

    var keys = Object.keys(argument);
    var chain = this;
    keys.forEach(function (key) {
      chain = call.bind(chain)(argument[key] * offset, key);
    });
    return chain;
  };

  proto.set = function (unit, value) {
    value = value === undefined ? unit : value;

    if (unit.constructor.name === 'Object') {
      return callObject.bind(this)(function (i, s) {
        return oldSet.bind(this)(s, i);
      }, value, unit);
    }

    return oldSet.bind(this)(unit, value);
  };

  proto.add = function (value, unit) {
    if (value.constructor.name === 'Object') {
      return callObject.bind(this)(oldAdd, value, unit);
    }

    return oldAdd.bind(this)(value, unit);
  };

  proto.subtract = function (value, unit) {
    if (value.constructor.name === 'Object') {
      return callObject.bind(this)(oldAdd, value, unit, -1);
    }

    return oldSubtract.bind(this)(value, unit);
  };
});