dayjs/esm/plugin/utc/index.js

import { MILLISECONDS_A_MINUTE, MIN } from '../../constant';
export default (function (option, Dayjs, dayjs) {
  var proto = Dayjs.prototype;

  dayjs.utc = function (date) {
    var cfg = {
      date: date,
      utc: true,
      args: arguments
    }; // eslint-disable-line prefer-rest-params

    return new Dayjs(cfg); // eslint-disable-line no-use-before-define
  };

  proto.utc = function (keepLocalTime) {
    var ins = dayjs(this.toDate(), {
      locale: this.$L,
      utc: true
    });

    if (keepLocalTime) {
      return ins.add(this.utcOffset(), MIN);
    }

    return ins;
  };

  proto.local = function () {
    return dayjs(this.toDate(), {
      locale: this.$L,
      utc: false
    });
  };

  var oldParse = proto.parse;

  proto.parse = function (cfg) {
    if (cfg.utc) {
      this.$u = true;
    }

    if (!this.$utils().u(cfg.$offset)) {
      this.$offset = cfg.$offset;
    }

    oldParse.call(this, cfg);
  };

  var oldInit = proto.init;

  proto.init = function () {
    if (this.$u) {
      var $d = this.$d;
      this.$y = $d.getUTCFullYear();
      this.$M = $d.getUTCMonth();
      this.$D = $d.getUTCDate();
      this.$W = $d.getUTCDay();
      this.$H = $d.getUTCHours();
      this.$m = $d.getUTCMinutes();
      this.$s = $d.getUTCSeconds();
      this.$ms = $d.getUTCMilliseconds();
    } else {
      oldInit.call(this);
    }
  };

  var oldUtcOffset = proto.utcOffset;

  proto.utcOffset = function (input, keepLocalTime) {
    var _this$$utils = this.$utils(),
        u = _this$$utils.u;

    if (u(input)) {
      if (this.$u) {
        return 0;
      }

      if (!u(this.$offset)) {
        return this.$offset;
      }

      return oldUtcOffset.call(this);
    }

    var offset = Math.abs(input) <= 16 ? input * 60 : input;
    var ins = this;

    if (keepLocalTime) {
      ins.$offset = offset;
      ins.$u = input === 0;
      return ins;
    }

    if (input !== 0) {
      var localTimezoneOffset = this.$u ? this.toDate().getTimezoneOffset() : -1 * this.utcOffset();
      ins = this.local().add(offset + localTimezoneOffset, MIN);
      ins.$offset = offset;
      ins.$x.$localOffset = localTimezoneOffset;
    } else {
      ins = this.utc();
    }

    return ins;
  };

  var oldFormat = proto.format;
  var UTC_FORMAT_DEFAULT = 'YYYY-MM-DDTHH:mm:ss[Z]';

  proto.format = function (formatStr) {
    var str = formatStr || (this.$u ? UTC_FORMAT_DEFAULT : '');
    return oldFormat.call(this, str);
  };

  proto.valueOf = function () {
    var addedOffset = !this.$utils().u(this.$offset) ? this.$offset + (this.$x.$localOffset || new Date().getTimezoneOffset()) : 0;
    return this.$d.valueOf() - addedOffset * MILLISECONDS_A_MINUTE;
  };

  proto.isUTC = function () {
    return !!this.$u;
  };

  proto.toISOString = function () {
    return this.toDate().toISOString();
  };

  proto.toString = function () {
    return this.toDate().toUTCString();
  };

  var oldToDate = proto.toDate;

  proto.toDate = function (type) {
    if (type === 's' && this.$offset) {
      return dayjs(this.format('YYYY-MM-DD HH:mm:ss:SSS')).toDate();
    }

    return oldToDate.call(this);
  };

  var oldDiff = proto.diff;

  proto.diff = function (input, units, _float) {
    if (input && this.$u === input.$u) {
      return oldDiff.call(this, input, units, _float);
    }

    var localThis = this.local();
    var localInput = dayjs(input).local();
    return oldDiff.call(localThis, localInput, units, _float);
  };
});