More elegant processing of dates in JavaScript based on Day.js

const today = new Date();
const dd = String(today.getDate()).padStart(2, '0'); // day const mm = String(today.getMonth() + 1).padStart(2, '0'); // month const yyyy = today.getFullYear(); // year const curDate = `${yyyy}-${mm}-${dd}`

console.log(curDate)
// Output: 2021-09-17

In day.js, we only need this, of course, it supports more than that, and many other functions.
import dayjs from "dayjs";

const curDate = dayjs().format('YYYY-MM-DD');

console.log(curDate)
// Output: 2021-09-17

import dayjs from "dayjs";

// The second parameter is specified as 'day', which means the granularity is day.dayjs(new Date(2021, 10, 1)).diff(new Date(2021, 9, 17), "day"); 
// Output: 15

import dayjs from "dayjs";

dayjs("20").isValid(); 
// Output: false
dayjs("2021-09-17").isValid(); 
// Output: true

import dayjs from "dayjs";

dayjs("2021-09-13").daysInMonth() 
// Output: 30

import dayjs from "dayjs";

dayjs("2021-09-17 08:10:00").add(20, "minute").format('YYYY-MM-DD HH:mm:ss') 
// Output: 2021-09-17 08:30:00

import dayjs from "dayjs";

dayjs("2021-09-17 08:10:00").subtract(20, "minute").format('YYYY-MM-DD HH:mm:ss')
// Output: 2021-09-17 07:50:00

import dayjs from "dayjs";
import relativeTime from "dayjs/plugin/relativeTime";

dayjs.extend(relativeTime);

dayjs("2021-09-16 13:28:55").fromNow();
// Output: 9 hours ago

import dayjs from "dayjs";
import weekOfYear from "dayjs/plugin/weekOfYear";

dayjs.extend(weekOfYear);

dayjs("2021-09-13 14:00:00").week(); 
// Output: 38

import dayjs from "dayjs";
import isSameOrAfter from "dayjs/plugin/isSameOrAfter";

dayjs.extend(isSameOrAfter);

dayjs("2021-09-17").isSameOrAfter("2021-09-16"); 
// Output: true

import dayjs from "dayjs";
import minMax from "dayjs/plugin/minMax";

dayjs.extend(minMax)

const maxDate = dayjs.max([
    dayjs("2021-09-13"), 
    dayjs("2021-09-16"), 
    dayjs("2021-09-20")
])

const minDate = dayjs.min([
    dayjs("2021-09-13"), 
    dayjs("2021-09-16"), 
    dayjs("2021-09-20")
])

maxDate.format('YYYY-MM-DD HH:mm:ss') 
// Output: 2021-09-20 00:00:00
minDate.format('YYYY-MM-DD HH:mm:ss') 
// Output: 2021-09-13 00:00:00

import dayjs from "dayjs";
import isBetween from "dayjs/plugin/isBetween";

dayjs.extend(isBetween);

// Use day as the granularity for comparison dayjs("2010-10-21").isBetween(dayjs("2010-10-20"), dayjs("2010-10-25"), "day");
// Output: true

// Use year as the granularity for comparison dayjs("2010-10-21").isBetween(dayjs("2010-10-20"), dayjs("2010-10-25"), "year");
// Output: false