JS foundation 6

Date time object Date

establish

1. Automatically get time

var date=new Date()

2. Create the specified date and time

var date=new Date('2021,3,18 00:00:00')

notes ：
It must be a string type
The value passed in is in years , month , Japan , when , branch , second , There is no zero filling processing

Method

Method	meaning
getTime()	Returns the number of milliseconds of the date
getFullYear()	return 4 Digit year
getMonth()	Returns the month of the date
getDate()	Returns the day of the date
getDay()	Returns the day of the week of the date
getHours()	Returns the hour in the date
getMinutes()	Returns the minute in the date
getSeconds()	Returns the second in the date
getMilliseconds()	Returns the number of milliseconds in the date

notes ：

1. From the month 0 Start counting
2. getDay() in 0 Means Sunday , The other is constant

Calculate the difference between two dates

1. The quasi change date is milliseconds
   notes ： Milliseconds is the time from the date to the origin of computer time （1970 year 1 month 1 Japan 0 when 0 branch 0 second ）
2. Millisecond difference
3. transformation

<script> function timeDiffer(m,n){ 
    
    var date1=new Date(m)
    var date2=new Date(n)
    // Calculate the milliseconds of the difference between two dates 
    var differdate=date1.getTime()-date2.getTime()
    // How many milliseconds a year 
    var yearTime=1000*60*60*24*365
    // How many years to round down 
    var year = Math.floor(differdate/yearTime) 
    console.log(year)
    // How many milliseconds a month 
    var monthTime=1000*60*60*24*30
    // The millisecond difference between the two dates minus the millisecond of last year 
    var differmonth=differdate-year*yearTime
    var month =Math.floor(differmonth/monthTime)
    console.log(month)
    var dayTime=1000*60*60*24
    var differday=differmonth-month*monthTime
    var day=Math.floor(differday/dayTime)
    console.log(day)
    var hourTime=1000*60*60
    var differhour=differday-day*dayTime
    var hour=Math.floor(differhour/hourTime)
    console.log(hour)
    var minuteTime=1000*60
    var differMinute=differhour-hour*hourTime
    var minute=Math.floor(differMinute/minuteTime)
    console.log(minute)
    var secondTime=1000
    var differSecond=differMinute-minute*minuteTime
    var second=Math.floor(differSecond/secondTime)
    console.log(second)
}
timeDiffer('2022-4-18 11:34:02','2022-2-18 8:30:00')
</script>

Date formatting method

Method	meaning
toString	Returns the date and time with time zone information
toDateString	Show the day of the week in the date , month , Japan , year
toTimeString	Display time , branch , second , And time zone
toLocaleDateString	Show the day of the week in the date , month , Japan , year
toLocaleTimeString	Display time , branch , second
toUTCString	Show complete UTC date

<script>
       var date=new Date()
       var date1=date.toString()
       var date2=date.toDateString()
       var date3=date.toTimeString()
       var date4=date.toLocaleDateString()
       var date5=date.toLocaleTimeString()
       var date6=date.toUTCString()
       console.log(date)
// result Sat Mar 19 2022 10:21:30 GMT+0800 ( China standard time )
       console.log(date1)
// result Sat Mar 19 2022 10:21:30 GMT+0800 ( China standard time )
       console.log(date2)
// result Sat Mar 19 2022
       console.log(date3)
// result 10:21:30 GMT+0800 ( China standard time )
       console.log(date4)
// result 2022/3/19
       console.log(date5)
// result 10:21:30
       console.log(date6)
// result Sat, 19 Mar 2022 02:21:30 GMT
    </script>