npm install dayjs
cnpm install dayjs -S
yarn add dayjs
pnpm add dayjs

var dayjs = require('dayjs')
// import dayjs from 'dayjs' // ES 2015
dayjs().format()

!function (t, n) { "object" == typeof exports && "undefined" != typeof module ? module.exports = n() : "function" == typeof define && define.amd ? define(n) : t.dayjs = n() }(this, function () { "use strict"; var t = "millisecond", n = "second", e = "minute", r = "hour", i = "day", s = "week", u = "month", o = "quarter", a = "year", h = /^(\d{4})-?(\d{1,2})-?(\d{0,2})[^0-9]*(\d{1,2})?:?(\d{1,2})?:?(\d{1,2})?.?(\d{1,3})?$/, f = /\[([^\]]+)]|Y{2,4}|M{1,4}|D{1,2}|d{1,4}|H{1,2}|h{1,2}|a|A|m{1,2}|s{1,2}|Z{1,2}|SSS/g, c = function (t, n, e) { var r = String(t); return !r || r.length >= n ? t : "" + Array(n + 1 - r.length).join(e) + t }, d = { s: c, z: function (t) { var n = -t.utcOffset(), e = Math.abs(n), r = Math.floor(e / 60), i = e % 60; return (n <= 0 ? "+" : "-") + c(r, 2, "0") + ":" + c(i, 2, "0") }, m: function (t, n) { var e = 12 * (n.year() - t.year()) + (n.month() - t.month()), r = t.clone().add(e, u), i = n - r < 0, s = t.clone().add(e + (i ? -1 : 1), u); return Number(-(e + (n - r) / (i ? r - s : s - r)) || 0) }, a: function (t) { return t < 0 ? Math.ceil(t) || 0 : Math.floor(t) }, p: function (h) { return { M: u, y: a, w: s, d: i, D: "date", h: r, m: e, s: n, ms: t, Q: o }[h] || String(h || "").toLowerCase().replace(/s$/, "") }, u: function (t) { return void 0 === t } }, $ = { name: "en", weekdays: "Sunday_Monday_Tuesday_Wednesday_Thursday_Friday_Saturday".split("_"), months: "January_February_March_April_May_June_July_August_September_October_November_December".split("_") }, l = "en", m = {}; m[l] = $; var y = function (t) { return t instanceof v }, M = function (t, n, e) { var r; if (!t) return l; if ("string" == typeof t) m[t] && (r = t), n && (m[t] = n, r = t); else { var i = t.name; m[i] = t, r = i } return e || (l = r), r }, g = function (t, n, e) { if (y(t)) return t.clone(); var r = n ? "string" == typeof n ? { format: n, pl: e } : n : {}; return r.date = t, new v(r) }, D = d; D.l = M, D.i = y, D.w = function (t, n) { return g(t, { locale: n.$L, utc: n.$u, $offset: n.$offset }) }; var v = function () { function c(t) { this.$L = this.$L || M(t.locale, null, !0), this.parse(t) } var d = c.prototype; return d.parse = function (t) { this.$d = function (t) { var n = t.date, e = t.utc; if (null === n) return new Date(NaN); if (D.u(n)) return new Date; if (n instanceof Date) return new Date(n); if ("string" == typeof n && !/Z$/i.test(n)) { var r = n.match(h); if (r) return e ? new Date(Date.UTC(r[1], r[2] - 1, r[3] || 1, r[4] || 0, r[5] || 0, r[6] || 0, r[7] || 0)) : new Date(r[1], r[2] - 1, r[3] || 1, r[4] || 0, r[5] || 0, r[6] || 0, r[7] || 0) } return new Date(n) }(t), this.init() }, d.init = function () { var t = this.$d; this.$y = t.getFullYear(), this.$M = t.getMonth(), this.$D = t.getDate(), this.$W = t.getDay(), this.$H = t.getHours(), this.$m = t.getMinutes(), this.$s = t.getSeconds(), this.$ms = t.getMilliseconds() }, d.$utils = function () { return D }, d.isValid = function () { return !("Invalid Date" === this.$d.toString()) }, d.isSame = function (t, n) { var e = g(t); return this.startOf(n) <= e && e <= this.endOf(n) }, d.isAfter = function (t, n) { return g(t) < this.startOf(n) }, d.isBefore = function (t, n) { return this.endOf(n) < g(t) }, d.$g = function (t, n, e) { return D.u(t) ? this[n] : this.set(e, t) }, d.year = function (t) { return this.$g(t, "$y", a) }, d.month = function (t) { return this.$g(t, "$M", u) }, d.day = function (t) { return this.$g(t, "$W", i) }, d.date = function (t) { return this.$g(t, "$D", "date") }, d.hour = function (t) { return this.$g(t, "$H", r) }, d.minute = function (t) { return this.$g(t, "$m", e) }, d.second = function (t) { return this.$g(t, "$s", n) }, d.millisecond = function (n) { return this.$g(n, "$ms", t) }, d.unix = function () { return Math.floor(this.valueOf() / 1e3) }, d.valueOf = function () { return this.$d.getTime() }, d.startOf = function (t, o) { var h = this, f = !!D.u(o) || o, c = D.p(t), d = function (t, n) { var e = D.w(h.$u ? Date.UTC(h.$y, n, t) : new Date(h.$y, n, t), h); return f ? e : e.endOf(i) }, $ = function (t, n) { return D.w(h.toDate()[t].apply(h.toDate(), (f ? [0, 0, 0, 0] : [23, 59, 59, 999]).slice(n)), h) }, l = this.$W, m = this.$M, y = this.$D, M = "set" + (this.$u ? "UTC" : ""); switch (c) { case a: return f ? d(1, 0) : d(31, 11); case u: return f ? d(1, m) : d(0, m + 1); case s: var g = this.$locale().weekStart || 0, v = (l < g ? l + 7 : l) - g; return d(f ? y - v : y + (6 - v), m); case i: case "date": return $(M + "Hours", 0); case r: return $(M + "Minutes", 1); case e: return $(M + "Seconds", 2); case n: return $(M + "Milliseconds", 3); default: return this.clone() } }, d.endOf = function (t) { return this.startOf(t, !1) }, d.$set = function (s, o) { var h, f = D.p(s), c = "set" + (this.$u ? "UTC" : ""), d = (h = {}, h[i] = c + "Date", h.date = c + "Date", h[u] = c + "Month", h[a] = c + "FullYear", h[r] = c + "Hours", h[e] = c + "Minutes", h[n] = c + "Seconds", h[t] = c + "Milliseconds", h)[f], $ = f === i ? this.$D + (o - this.$W) : o; if (f === u || f === a) { var l = this.clone().set("date", 1); l.$d[d]($), l.init(), this.$d = l.set("date", Math.min(this.$D, l.daysInMonth())).toDate() } else d && this.$d[d]($); return this.init(), this }, d.set = function (t, n) { return this.clone().$set(t, n) }, d.get = function (t) { return this[D.p(t)]() }, d.add = function (t, o) { var h, f = this; t = Number(t); var c = D.p(o), d = function (n) { var e = g(f); return D.w(e.date(e.date() + Math.round(n * t)), f) }; if (c === u) return this.set(u, this.$M + t); if (c === a) return this.set(a, this.$y + t); if (c === i) return d(1); if (c === s) return d(7); var $ = (h = {}, h[e] = 6e4, h[r] = 36e5, h[n] = 1e3, h)[c] || 1, l = this.$d.getTime() + t * $; return D.w(l, this) }, d.subtract = function (t, n) { return this.add(-1 * t, n) }, d.format = function (t) { var n = this; if (!this.isValid()) return "Invalid Date"; var e = t || "YYYY-MM-DDTHH:mm:ssZ", r = D.z(this), i = this.$locale(), s = this.$H, u = this.$m, o = this.$M, a = i.weekdays, h = i.months, c = function (t, r, i, s) { return t && (t[r] || t(n, e)) || i[r].substr(0, s) }, d = function (t) { return D.s(s % 12 || 12, t, "0") }, $ = i.meridiem || function (t, n, e) { var r = t < 12 ? "AM" : "PM"; return e ? r.toLowerCase() : r }, l = { YY: String(this.$y).slice(-2), YYYY: this.$y, M: o + 1, MM: D.s(o + 1, 2, "0"), MMM: c(i.monthsShort, o, h, 3), MMMM: h[o] || h(this, e), D: this.$D, DD: D.s(this.$D, 2, "0"), d: String(this.$W), dd: c(i.weekdaysMin, this.$W, a, 2), ddd: c(i.weekdaysShort, this.$W, a, 3), dddd: a[this.$W], H: String(s), HH: D.s(s, 2, "0"), h: d(1), hh: d(2), a: $(s, u, !0), A: $(s, u, !1), m: String(u), mm: D.s(u, 2, "0"), s: String(this.$s), ss: D.s(this.$s, 2, "0"), SSS: D.s(this.$ms, 3, "0"), Z: r }; return e.replace(f, function (t, n) { return n || l[t] || r.replace(":", "") }) }, d.utcOffset = function () { return 15 * -Math.round(this.$d.getTimezoneOffset() / 15) }, d.diff = function (t, h, f) { var c, d = D.p(h), $ = g(t), l = 6e4 * ($.utcOffset() - this.utcOffset()), m = this - $, y = D.m(this, $); return y = (c = {}, c[a] = y / 12, c[u] = y, c[o] = y / 3, c[s] = (m - l) / 6048e5, c[i] = (m - l) / 864e5, c[r] = m / 36e5, c[e] = m / 6e4, c[n] = m / 1e3, c)[d] || m, f ? y : D.a(y) }, d.daysInMonth = function () { return this.endOf(u).$D }, d.$locale = function () { return m[this.$L] }, d.locale = function (t, n) { if (!t) return this.$L; var e = this.clone(), r = M(t, n, !0); return r && (e.$L = r), e }, d.clone = function () { return D.w(this.$d, this) }, d.toDate = function () { return new Date(this.valueOf()) }, d.toJSON = function () { return this.isValid() ? this.toISOString() : null }, d.toISOString = function () { return this.$d.toISOString() }, d.toString = function () { return this.$d.toUTCString() }, c }(); return g.prototype = v.prototype, g.extend = function (t, n) { return t(n, v, g), g }, g.locale = M, g.isDayjs = y, g.unix = function (t) { return g(1e3 * t) }, g.en = m[l], g.Ls = m, g });

!function (r, e) { "object" == typeof exports && "undefined" != typeof module ? module.exports = e() : "function" == typeof define && define.amd ? define(e) : (r = "undefined" != typeof globalThis ? globalThis : r || self).dayjs_plugin_relativeTime = e() }(this, (function () { "use strict"; return function (r, e, t) { r = r || {}; var n = e.prototype, o = { future: "in %s", past: "%s ago", s: "a few seconds", m: "a minute", mm: "%d minutes", h: "an hour", hh: "%d hours", d: "a day", dd: "%d days", M: "a month", MM: "%d months", y: "a year", yy: "%d years" }; function i(r, e, t, o) { return n.fromToBase(r, e, t, o) } t.en.relativeTime = o, n.fromToBase = function (e, n, i, d, u) { for (var f, a, s, l = i.$locale().relativeTime || o, h = r.thresholds || [{ l: "s", r: 44, d: "second" }, { l: "m", r: 89 }, { l: "mm", r: 44, d: "minute" }, { l: "h", r: 89 }, { l: "hh", r: 21, d: "hour" }, { l: "d", r: 35 }, { l: "dd", r: 25, d: "day" }, { l: "M", r: 45 }, { l: "MM", r: 10, d: "month" }, { l: "y", r: 17 }, { l: "yy", d: "year" }], m = h.length, c = 0; c < m; c += 1) { var y = h[c]; y.d && (f = d ? t(e).diff(i, y.d, !0) : i.diff(e, y.d, !0)); var p = (r.rounding || Math.round)(Math.abs(f)); if (s = f > 0, p <= y.r || !y.r) { p <= 1 && c > 0 && (y = h[c - 1]); var v = l[y.l]; u && (p = u("" + p)), a = "string" == typeof v ? v.replace("%d", p) : v(p, n, y.l, s); break } } if (n) return a; var M = s ? l.future : l.past; return "function" == typeof M ? M(a) : M.replace("%s", a) }, n.to = function (r, e) { return i(r, e, this, !0) }, n.from = function (r, e) { return i(r, e, this) }; var d = function (r) { return r.$u ? t.utc() : t() }; n.toNow = function (r) { return this.to(d(this), r) }, n.fromNow = function (r) { return this.from(d(this), r) } } }));

!function(e,_){"object"==typeof exports&&"undefined"!=typeof module?module.exports=_(require("dayjs")):"function"==typeof define&&define.amd?define(["dayjs"],_):(e="undefined"!=typeof globalThis?globalThis:e||self).dayjs_locale_zh_cn=_(e.dayjs)}(this,(function(e){"use strict";function _(e){return e&&"object"==typeof e&&"default"in e?e:{default:e}}var t=_(e),d={name:"zh-cn",weekdays:"星期日_星期一_星期二_星期三_星期四_星期五_星期六".split("_"),weekdaysShort:"周日_周一_周二_周三_周四_周五_周六".split("_"),weekdaysMin:"日_一_二_三_四_五_六".split("_"),months:"一月_二月_三月_四月_五月_六月_七月_八月_九月_十月_十一月_十二月".split("_"),monthsShort:"1月_2月_3月_4月_5月_6月_7月_8月_9月_10月_11月_12月".split("_"),ordinal:function(e,_){return"W"===_?e+"周":e+"日"},weekStart:1,yearStart:4,formats:{LT:"HH:mm",LTS:"HH:mm:ss",L:"YYYY/MM/DD",LL:"YYYY年M月D日",LLL:"YYYY年M月D日Ah點(diǎn)mm分",LLLL:"YYYY年M月D日ddddAh點(diǎn)mm分",l:"YYYY/M/D",ll:"YYYY年M月D日",lll:"YYYY年M月D日 HH:mm",llll:"YYYY年M月D日dddd HH:mm"},relativeTime:{future:"%s內(nèi)",past:"%s前",s:"幾秒",m:"1 分鐘",mm:"%d 分鐘",h:"1 小時(shí)",hh:"%d 小時(shí)",d:"1 天",dd:"%d 天",M:"1 個(gè)月",MM:"%d 個(gè)月",y:"1 年",yy:"%d 年"},meridiem:function(e,_){var t=100*e+_;return t<600?"凌晨":t<900?"早上":t<1100?"上午":t<1300?"中午":t<1800?"下午":"晚上"}};return t.default.locale(d,null,!0),d}));

<script src="./libs/day.js"></script>
// 會(huì)在Dayjs的原型上添加: formNow
<script src="./libs/dayjs.relative-time.js"></script>

//給dayjs的全局變量Ls添加一個(gè)中文支持
<script src="./libs/dayjs.zh-cn.js"></script>
// 1.安裝插件
dayjs.extend(dayjs_plugin_relativeTime)
dayjs.locale('zh-cn')
//1. 1個(gè)小時(shí) 5分鐘 2天前
var day = dayjs(1656206934331)
console.log(day.fromNow())

<script src="./libs/day.js"></script>


//基礎(chǔ)寫(xiě)法
// 1.拿到Dayjs的效果
var day = dayjs()

// 獲取時(shí)間
console.log(day.year(),(day.month()+1),day.date(),day.hour(),day.minute(),day.second())


//高階寫(xiě)法
var day = dayjs()
          .year(2021)
          .month(5)
          .date(1)
console.log(day.year(),(day.month()+1),day.date(),day.hour(),day.minute(),day.second())

<script src="./libs/day.js"></script>

//增加一天
var day = dayjs()
    .add(1, 'day')
    .startOf('year')
    .startOf('month');

console.log(day.format("YYYY-MM-DD HH:mm:ss"));

<script src="./libs/day.js"></script>

// 1. 解析一個(gè)字符串類型的時(shí)間
// YYYY-MM-DD HH:mm:ss
// YYYY-MM-DD
// YYYY/MM/DD
var day1 = dayjs('2021-2-2 12:00:10');

// 2.解析時(shí)間戳(毫秒)
var day2 = dayjs(1656206934331);

// 3.解析時(shí)間戳(秒)
var day3 = dayjs.unix(1656206934);

// 4.解析data對(duì)象
var day4 = dayjs(new Date('2022-10-1'));

// 時(shí)間的格式化
console.log(day1.format("YYYY-MM-DD HH:mm:ss")); // 格式化輸出日期時(shí)間

;(function(g){
    //browser -> window ; 
    //node -> global

    //globalThis -> ES11
    g = typeof globalThis !== 'undefined' ? globalThis : g || self

    
    //構(gòu)造函數(shù)
    function Dayjs(){
        var date = new Date()
        this.$Y = date.getFullYear()
        this.$M = date.getMonth()
        this.$D = date.getDate()
    }
    Dayjs.prototype.format = function(){
        return `${this.$Y}-${(this.$M+1)}-${this.$D}`
    }
    // ....原型的方法
    // ....原型的方法
    // ....原型的方法
    // ....原型的方法
    // ....原型的方法
    // ....原型的方法
    // ....原型的方法


    //工廠函數(shù)
    function dayjs(){
        return new Dayjs()
    }
    dayjs.prototype = Dayjs.prototype
    //統(tǒng)一導(dǎo)出
    g.dayjs = dayjs
})(this)

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script src="./utils/JYDayjs.js"></script>
    <script>
        console.log("%O", dayjs)
        console.log("%O", dayjs())// 創(chuàng)建dayjs對(duì)象
        console.log(dayjs().format()) //拿到當(dāng)前的時(shí)間
    </script>
</body>

</html>

(function(g){
    g = typeof globalThis !== 'undefined' ? globalThis : g || self;

    // 構(gòu)造函數(shù)
    function Dayjs(dateString) {
        if (dateString) {
            var parsedDate = new Date(dateString);
            if (isNaN(parsedDate.getTime())) {
                throw new Error('Invalid date format');
            }
            this.$Y = parsedDate.getFullYear();
            this.$M = parsedDate.getMonth();
            this.$D = parsedDate.getDate();
        } else {
            var currentDate = new Date();
            this.$Y = currentDate.getFullYear();
            this.$M = currentDate.getMonth();
            this.$D = currentDate.getDate();
        }
    }

    // 格式化日期
    Dayjs.prototype.format = function(formatString = 'YYYY-MM-DD') {
        const year = this.$Y;
        const month = (this.$M + 1).toString().padStart(2, '0');
        const day = this.$D.toString().padStart(2, '0');

        return formatString.replace(/YYYY/g, year)
                            .replace(/MM/g, month)
                            .replace(/DD/g, day);
    }

    // 工廠函數(shù)
    function dayjs(dateString) {
        return new Dayjs(dateString);
    }

    // 原型鏈處理
    dayjs.prototype = Object.create(Dayjs.prototype);
    dayjs.prototype.constructor = dayjs;

    // 導(dǎo)出
    g.dayjs = dayjs;
})(this);