Js various time conversion problems (YYYY-MM-DD timestamp Chinese standard time)

1. Type summary

Specify the format YYYY-MM-DD HH:MM:SS
timestamp
China Standard Time Sat Jan 30 2022 08:26:26 GMT+0800 (China Standard Time) new Date()to obtain the current time of the system will be in this form

2. Conversion between types

Timestamp converted to yyyy-mm-dd or yyyy-MM-dd HH-mm-ss

function timestampToTime(timestamp) {
    
    
        var date = new Date(timestamp * 1000);//时间戳为10位需*1000，时间戳为13位的话不需乘1000
        var Y = date.getFullYear() + '-';
        var M = (date.getMonth()+1 < 10 ? '0'+(date.getMonth()+1):date.getMonth()+1) + '-';
        var D = (date.getDate()< 10 ? '0'+date.getDate():date.getDate())+ ' ';
        var h = (date.getHours() < 10 ? '0'+date.getHours():date.getHours())+ ':';
        var m = (date.getMinutes() < 10 ? '0'+date.getMinutes():date.getMinutes()) + ':';
        var s = date.getSeconds() < 10 ? '0'+date.getSeconds():date.getSeconds();
        return Y+M+D+h+m+s;
    }

yyyy-mm-dd or yyyy-MM-dd HH-mm-ss to timestamp

var stringTime = '2012-10-12 22:37:33';
//将获取到的时间转换成时间戳
var timestamp = Date.parse(new Date(stringTime));

China Standard Time to yyyy-mm-dd hh-mm-ss

 let y = date.getFullYear()
 let m = date.getMonth() + 1
 m = m < 10 ? ('0' + m) : m
 let d = date.getDate()
 d = d < 10 ? ('0' + d) : d
 let h =date.getHours()
 h = h < 10 ? ('0' + h) : h
 let M =date.getMinutes()
 M = M < 10 ? ('0' + M) : M
 let s =date.getSeconds()
 s = s < 10 ? ('0' + s) : s
 let dateTime= y + '-' + m + '-' + d + ' ' + h + ':' + M + ':' + s;

yyyy-mm-dd hh-mm-ss to China Standard Time
1. new Date("month dd,yyyy hh:mm:ss");
2. new Date("month dd,yyyy");
3. new Date (yyyy,mth,dd,hh,mm,ss); Note: In this way, integer must be passed;
4. new Date(yyyy,mth,dd);
5. new Date(ms); Note: ms: It is the number of milliseconds between the time that needs to be created and GMT time January 1, 1970; the number of milliseconds between the current time and GMT1970.1.1: var mills = new Date().getTime();
Timestamp converted to China Standard Time

const time = 1531065600000；//时间戳（数字）
const youData = new Data(time);

Convert China Standard Time to Timestamp

Date.parse(Time)

3. Date type

Create date object let now = new Date();
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When no parameters are passed to the Date constructor, the created object will hold the current date and time. To create a date object based on other dates and times, you need to pass in the millisecond representation.

Types: Date.parse() && Date.UTC() && Date.now() && Date.toLocaleString() && Date.toString()

Parameter types supported by Date.parse()
: 1) month/day/year eg: '1/18/2023'
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2) month name day, year eg: 'May 23, 2019'

3) week month name day year time : Minutes: Seconds Time zone eg: 'Wed Jan 18 2023 16:21:53 GMT+0800'

4) YYYY-MM-DDTHH:mm:ss.sssZ eg: 2019-05-23T00:00:00

If the parameter passed in Does not represent a date, returns NaN

Usage :

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Date.UTC()
0:00, January 1, 2000,

5:55:55 pm, May 5, 2005 (note that the month starts from 0)

Date.now() current time
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Date.toLocaleString() && Date.toString()

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4. Date formatting

toDateString()
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toTimeString()
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toLocaleDateString()
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toLocaleTimeString()
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toUTCString()
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5. How to judge whether it is the time of the day

if (new Date(str).toDateString() === new Date().toDateString()) {
    
    
    //今天
    console.log("当天");
} else if (new Date(str) < new Date()){
    
    
    //之前
    console.log(new Date(str).toISOString().slice(0,10));
}