How to get the n umber of days left until a specific day-CodePudding

How can I get the number of days left until next birthday from this array of objects?

const people = [
    { name: 'Bill', dob: new Date('07/11/1949') },
    { name: 'Will', dob: new Date('02/21/1979') }
]

So basically I need how many days there are from today until the birth date.

I tried to extract the month and day from the dob like this:

for (let i = 0; i < people.length; i  ) {
    const personDob = people[i].dob
    const personBirthMonth = new Date(personDob).getMonth()   1
    const personDayOfBirth = new Date(personDob).getUTCDate()  1
}

I've checked this post but I'm kind of confused because I don't need to compare the full year, only the months and days I guess.

I'm not sure how to get the remaining days left.

CodePudding user response：

Do you mean this?

If the date is past, then plus one year on the year of now.

Just a simple example, please modify yourself.

So code:

const now = new Date(),
    date = new Date("07/11/1949");

if (now.getMonth() > date.getMonth() || (now.getMonth() == date.getMonth() && now.getDate() > date.getDate()))
    date.setFullYear(now.getFullYear()   1);
const days = (date.getTime() - now.getTime()) / 86400000;
console.log(days   " days left.");

CodePudding user response：

May you could try to extract like this

currDate = new Date()
people.forEach((person)=>{
     let nextbd = person.dob;
     nextbd.setFullYear(currDate.getFullYear()   1);
     let diffTime = Math.abs(nextbd  - currDate);
     let diffDays = Math.ceil(diffTime / (1000 * 60 * 60 * 24)); 

   console.log(person.name " has next birdthday after "  diffDays  " days");
     
})

CodePudding user response：

So you basically want to know the days remaining till the birthday of a person.

Let's say someone has a birthday on 21 September 2022, the code for such will go like this. Also, feel free to fix it according to your situation.

 function getNumberOfDays(today, birthday) {
        const date1 = new Date(today);
        const date2 = new Date(birthday);
    
        // One day in milliseconds
        const oneDay = 1000 * 60 * 60 * 24;
    
        // Calculating the time difference between two dates
        const diffInTime = date2.getTime() - date1.getTime();
    
        // Calculating the no. of days between two dates
        const diffInDays = Math.round(diffInTime / oneDay);
    
        return diffInDays;
    }
    var today = new Date();
    var dd = String(today.getDate()).padStart(2, '0');
    var mm = String(today.getMonth()   1).padStart(2, '0');
    var yyyy = today.getFullYear();
    console.log(getNumberOfDays(`${mm}/${dd}/${yyyy}`,"9/21/2022", ));