JavaScript validate date and return last available date of calendar

Question

I want to validate my date if date not exits in calendar then return me last available date of calendar,

Example 01

Input Date    : 31         


        

Answer 1

function isValidDate(year, month, day) {
    var d = new Date(year, month, day);
    if (d.getFullYear() == year && d.getMonth() == month && d.getDate() == day) {
        return d;
    }
    else
        rturn new Date(year, month, 0);;
}

Answer 2

You can try something like this:

Explanation as per spec:

When we call date constructor with 2 or more arguments, it tries to process using following constructor ref:

new Date (year, month [, date [, hours [, minutes [, seconds [, ms ] ] ] ] ] )

Here if any value that is not passed, it will be set as NaN and later will be parsed to +0. Hence timestamp is 0:0:0

Now the trick is in a function called internally: MakeDay.

As you see point 8, it returns

Day(t) + dt − 1

Here Day(t) would return number of milliseconds and date would be calculated based on dt - 1. Since we are passing 0, date value would be -1 + milliseconds and hence it returns previous day.

Another alternate would be to create date for 1st of next month and subtract 1 as day or sec. You can select anyone based on the need,

function isValidDate(year, month, day) {
  var d = new Date(year, month, day);
  return !!(d.getFullYear() == year && d.getMonth() == month && d.getDate() == day)
}

function computeLastPossibleDate(y,m,d){
  return new Date(y, m+1, 0);
}

function test(y,m,d){
  return isValidDate(y,m,d) ? new Date(y,m,d) : computeLastPossibleDate(y,m,d)
}

// 31st Feb.
console.log(test(2017, 1, 31).toString())
// 31st March
console.log(test(2017, 2, 31).toString())
// 31st April
console.log(test(2017, 3, 31).toString())
// 50th Dec.
console.log(test(2017, 11, 50).toString())

Note: If there is anything missing, please share it as a comment with your vote. Just vote without comment will not help anyone.

Answer 3

  function isValidDate(year, month, day) {
    if(month<=12){

        var temp_day=day;
        var d = new Date(year, month, day);
        var lastDay = new Date(d.getFullYear(), d.getMonth(),0);
        var getlastday=lastDay.getDate();
        if(getlastday<=day){
            //var date=(d.getDate())+"/"+(d.getMonth())+"/"+(d.getFullYear());
            var date=(getlastday)+"-"+(month)+"-"+(lastDay.getFullYear());
            return date;
        }else{
            //var date=(lastDay.getDate())+"-"+(lastDay.getMonth())+"-"+(lastDay.getFullYear());
            var date=(day)+"/"+(month)+"/"+(year);
            return date;
        }
    }
    else{
        return "month not valid";
    }
}

try this code

Answer 4

The last day of the month is given by the zero day of the following month, so:

function getDate(year, month, day) {
    var d = new Date(year, month, day);
    if (d.getMonth() == month) {
        return d;
    }
    return new Date(year, +month + 1, 0);
}

console.log(getDate(2017,1,29).toString());
console.log(getDate(2017,0,32).toString());

BTW, to test for a valid date you only need to test the month since if the month is larger than months in a year, it will affect both month and year. If the day is greater than the number of days in the month it will affect the month too. Nothing affects the year (unless you pass a year less than 100, in which case it's treated as 1900 + year).