Incrementing a date in JavaScript

Tomorrow in one line in pure JS but it's ugly !

new Date(new Date().setDate(new Date().getDate() + 1))

Here is the result :

Thu Oct 12 2017 08:53:30 GMT+0200 (Romance Summer Time)

I feel that nothing is safer than .getTime() and .setTime(), so this should be the best, and performant as well.

const d = new Date()
console.log(d.setTime(d.getTime() + 1000 * 60 * 60 * 24)) // MILLISECONDS

.setDate() for invalid Date (like 31 + 1) is too dangerous, and it depends on the browser implementation.

Via native JS, to add one day you may do following:

let date = new Date(); // today
date.setDate(date.getDate() + 1) // tomorrow

Another option is to use moment library:

const date = moment().add(14, "days").toDate()

 Date.prototype.AddDays = function (days) {
    days = parseInt(days, 10);
    return new Date(this.valueOf() + 1000 * 60 * 60 * 24 * days);
}

Example

var dt = new Date();
console.log(dt.AddDays(-30));
console.log(dt.AddDays(-10));
console.log(dt.AddDays(-1));
console.log(dt.AddDays(0));
console.log(dt.AddDays(1));
console.log(dt.AddDays(10));
console.log(dt.AddDays(30));

Result

2017-09-03T15:01:37.213Z
2017-09-23T15:01:37.213Z
2017-10-02T15:01:37.213Z
2017-10-03T15:01:37.213Z
2017-10-04T15:01:37.213Z
2017-10-13T15:01:37.213Z
2017-11-02T15:01:37.213Z

Incrementing date's year with vanilla js:

start_date_value = "01/01/2019"
var next_year = new Date(start_date_value);
next_year.setYear(next_year.getYear() + 1);
console.log(next_year.getYear()); //=> 2020

Just in case someone wants to increment other value than the date (day)

Timezone/daylight savings aware date increment for JavaScript dates:

function nextDay(date) {
    const sign = v => (v < 0 ? -1 : +1);
    const result = new Date(date.getTime());
    result.setDate(result.getDate() + 1);
    const offset = result.getTimezoneOffset();
    return new Date(result.getTime() + sign(offset) * offset * 60 * 1000);
}

This a simpler method , and it will return the date in simple yyyy-mm-dd format , Here it is

function incDay(date, n) {
    var fudate = new Date(new Date(date).setDate(new Date(date).getDate() + n));
    fudate = fudate.getFullYear() + '-' + (fudate.getMonth() + 1) + '-' + fudate.toDateString().substring(8, 10);
    return fudate;
}

example :

var tomorrow = incDay(new Date(), 1); // the next day of today , aka tomorrow :) .
var spicaldate = incDay("2020-11-12", 1); // return "2020-11-13" .
var somedate = incDay("2020-10-28", 5); // return "2020-11-02" .

Note

incDay(new Date("2020-11-12"), 1); 
incDay("2020-11-12", 1); 

will return the same result .

Use this function, it´s solved my problem:

    let nextDate = (daysAhead:number) => {
      const today = new Date().toLocaleDateString().split('/')
      const invalidDate = new Date(`${today[2]}/${today[1]}/${Number(today[0])+daysAhead}`)
      if(Number(today[1]) === Number(12)){
        return new Date(`${Number(today[2])+1}/${1}/${1}`)
      }
      if(String(invalidDate) === 'Invalid Date'){
        return new Date(`${today[2]}/${Number(today[1])+1}/${1}`)
      }
        return new Date(`${today[2]}/${Number(today[1])}/${Number(today[0])+daysAhead}`)
    }

Assigning the Increment of current date to other Variable

 let startDate=new Date();
 let endDate=new Date();    
 endDate.setDate(startDate.getDate() + 1)
 console.log(startDate,endDate)