JavaScript calculating date from today date to 7 days before

问题

I am calculating 12 days before date from today date. But it does not return the correct date. For example, for today dat, 11/11/2013 in (mm/dd/yyyy), it returns 10/30/2013 when it should return 10/31/2013.

Here is the code

var d = new Date();
d.setDate(d.getDate() - 12);
d.setMonth(d.getMonth() + 1 - 0);
var curr_date = d.getDate();
var curr_month = d.getMonth();
var curr_year = d.getFullYear();
if (curr_month < 10 && curr_date < 10) {
    var parsedDate = "0" + curr_month + "/" + "0" + curr_date + "/" + curr_year;
    alert(parsedDate);
} else if (curr_month < 10 && curr_date > 9) {
    var parsedDate = "0" + curr_month + "/" + curr_date + "/" + curr_year;
    alert(parsedDate);
} else if (curr_month > 9 && curr_date < 10) {
    var parsedDate = curr_month + "/" + "0" + curr_date + "/" + curr_year;
    alert(parsedDate);
} else {
    var parsedDate = curr_month + "/" + curr_date + "/" + curr_year;
    alert(parsedDate);
}

回答1:

Problem is solved

var days; // Days you want to subtract
var date = new Date();
var last = new Date(date.getTime() - (days * 24 * 60 * 60 * 1000));
var day =last.getDate();
var month=last.getMonth()+1;
var year=last.getFullYear();

回答2:

Pure js one line solution:

new Date(Date.now() - 7 * 24 * 60 * 60 * 1000)  // Tue Feb 04 2020 13:50:37 GMT...

new Date() - create Date object from calculated milliseconds time.
Date.now() - gives time in milliseconds from 1970.
7 (days) * 24 (hours) * 60 (minutes) * 60 (seconds) * 1000 (milliseconds ) = 604800000 or 7 days in milliseconds.

You can use calculated value if you have no plans to change substracted value, or computed for easy change of substracted amount of days, minutes and so on.

If you plan to work more often with dates and time, i recommend to use moment.js

moment().subtract(7, 'days').toDate()

回答3:

You can use the following code to get the date from today date to 7 days before

var date = new Date();
date.setDate(date.getDate() - 7);

var finalDate = date.getDate()+'/'+ (date.getMonth()+1) +'/'+date.getFullYear();

回答4:

Trying to subtract days is tricky. It would be better to subtract from the timestamp and change the date.

To subtract 12 days do:

   var d = new Date();
   var ts = d.getTime();
   var twelveDays = ts - (12 * 24 * 60 * 60 * 1000);
   d.setUTCDate(twelveDays);

回答5:

Updated :)

var timeFrom = (X) => {
    var dates = [];
    for (let I = 0; I < Math.abs(X); I++) {
        dates.push(new Date(new Date().getTime() - ((X >= 0 ? I : (I - I - I)) * 24 * 60 * 60 * 1000)).toLocaleString());
    }
    return dates;
}
console.log(timeFrom(-7)); // Future 7 Days
console.log(timeFrom(7)); // Past 7 Days

Output

[
  '7/26/2019, 3:08:15 PM',
  '7/27/2019, 3:08:15 PM',
  '7/28/2019, 3:08:15 PM',
  '7/29/2019, 3:08:15 PM',
  '7/30/2019, 3:08:15 PM',
  '7/31/2019, 3:08:15 PM',
  '8/1/2019, 3:08:15 PM'
]
[
  '7/26/2019, 3:08:15 PM',
  '7/25/2019, 3:08:15 PM',
  '7/24/2019, 3:08:15 PM',
  '7/23/2019, 3:08:15 PM',
  '7/22/2019, 3:08:15 PM',
  '7/21/2019, 3:08:15 PM',
  '7/20/2019, 3:08:15 PM'
]

回答6:

To get past days as Array use this code

See the console for result

const GetDays = (d,Mention_today=false)=>{
//Mention today mean the array will have today date 
var DateArray = [];
var days=d;
for(var i=0;i<days;i++){
if(!Mention_today && i==0){i=1;days+=1}
var date = new Date();
var last = new Date(date.getTime() - (i * 24 * 60 * 60 * 1000));
var day =last.getDate();
var month=last.getMonth()+1;
var year=last.getFullYear();
const fulld = (Number(year)+'-'+Number(month)+'-'+Number(day)) // Format date as you like
DateArray.push(fulld);
}
return DateArray;
}

console.log(GetDays(5)) //Will get the past 5 days formated YY-mm-dd

回答7:

Date.prototype.addDays = function(days) {
    // Add days to given date
    var date = new Date(this.valueOf());
    date.setDate(date.getDate() + days);
    return date;
}

let today = new Date()

console.log(today.addDays(-7))

回答8:

Here is a function that returns date in past or in future based on below;

If plusMinus = -1 then Past Date
If plusMinus = 1 then Future Date

function getDate(inDays, plusMinus) {
    const today = new Date(); 
    return new Date(today.getFullYear(),
                    today.getMonth(),
                    today.getDate() + (inDays * plusMinus));
}

回答9:

Using dayjs library, we can do it easier.

import dayjs from 'dayjs';

const getDate = (prevDays) => {
    const now = dayjs();
    console.log(now.subtract(prevDays, 'day').format('mm-dd-yyyy'));
    return now.subtract(prevDays, 'day').toDate();
}

回答10:

Here is best solution.. when X is your day:

var dates = [];
for (let i = 0; i < X; i++) {
  var date = new Date();

  var thatDay = date.getDate() - i; //Current Date
  date.setDate(thatDay);
  let day = date.getDate();
  let month = date.getMonth() + 1;
  let year = date
    .getFullYear()
    .toString()
    .substr(-2);

  dates.push(month + '/' + day + '/' + year); //format it as you need
}
//output mm/d/yy

来源：https://stackoverflow.com/questions/19910161/javascript-calculating-date-from-today-date-to-7-days-before

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javascript

date