days left until user's bday-CodePudding

I've created a pirate speak program.

It asks the user for their name and date of birth and calculates the years from the input and added 100 years for fun. I also need to calculate the number of days left until their birthday using user input but I don't know what to do. I've tried some methods and stuff but its not working. any tips or mistakes I need to fix?

var name = prompt('What\'s yer name?');

var date = prompt('What\'s yer date o\' birth? (mm/dd/yyyy)');

let years = date;

let num = years.substring(6, 10);

var myInput = parseInt(num);

var x = myInput;

var y = 100; 

var result = x   y;

console.log(`Ahoy, ${name}. It will be th\' year ${result} when ye be 100 years barnacle-covered.`);    

var myInput = parseInt(date);

var bday = myInput;

function daysUntilNext(month, day){
    var tday= new Date(), y= tday.getFullYear(), next= new Date(y, month-1, day);
    tday.setHours(0, 0, 0, 0);
    if(tday>next) next.setFullYear(y 1);
    return Math.round((next-tday)/8.64e7);
}

var d= daysUntilNext(date); 

console.log(d ' day' (d>1? 's': '') ' until yer birthday');

CodePudding user response：

Ok, I have cleaned up your JavaScript a little. Best practice was to get the date from the string and parse each part then just create a Date object from there. What's easier in the future is to use a datepicker HTML component rather than a string, but I understand that wasn't your goal for this.

Next, do the plus 100 calculation and display that result.

Lastly, take the Date object we made and take the information that we need from it. FWIW getDay() returns the day of the week, you want getDate() which return the day of the month. Then calculate how many days away from those in the next year. Display that result in the console.

I think you were getting that NAN because you were doing calculations on strings not numbers or it was because there weren't enough parameters in daysUntilNext(), so you were operating on null or undefined somewhere

var name = prompt('What\'s yer name?');

var birthDateString = prompt('What\'s yer date o\' birth? (mm/dd/yyyy)');
var daySubstring = birthDateString.substring(3, 5);
var monthSubstring = birthDateString.substring(0, 2);
var yearSubstring = birthDateString.substring(6, 10);
var birthdate = new Date(parseInt(yearSubstring), parseInt(monthSubstring) - 1, parseInt(daySubstring));

var ONE_HUNDRED = 100;

var result = parseInt(yearSubstring)   ONE_HUNDRED;

console.log(`Ahoy, ${name}. It will be th\' year ${result} when ye be 100 years barnacle-covered.`);

function daysUntilNext(month, day) {
  var today = new Date();
  var year = today.getFullYear();
  
  var next = new Date(year, month, day);
  today.setHours(0, 0, 0, 0);
  
  if (today > next) next.setFullYear(year   1);
  return Math.round((next - today) / 8.64e7);
}

var d = daysUntilNext(birthdate.getMonth(), birthdate.getDate());

console.log(d   ' day'   (d > 1 ? 's' : '')   ' until yer birthday');

CodePudding user response：

The other answerer's code is correct, but not clear. Here's the same, only more user-friendly.

The difference is that single-digit months or days won't bother you.

I hope I could help.

var name = prompt('What\'s yer name?');

var birthDateString = prompt('What\'s yer date o\' birth? (mm/dd/yyyy)');
var inputdate = birthDateString.split("/");
var daySubstring = inputdate[1];
var monthSubstring = inputdate[0];
var yearSubstring = inputdate[2];
var birthdate = new Date(parseInt(yearSubstring), parseInt(monthSubstring) - 1, parseInt(daySubstring));

var ONE_HUNDRED = 100;

var result = parseInt(yearSubstring)   ONE_HUNDRED;

console.log(`Ahoy, ${name}. It will be th\' year ${result} when ye be 100 years barnacle-covered.`);

function daysUntilNext(month, day) {
  var today = new Date();
  var year = today.getFullYear();
  
  var next = new Date(year, month, day);
  today.setHours(0, 0, 0, 0);
  
  if (today > next) next.setFullYear(year   1);
  return Math.round((next - today) / 8.64e7);
}

var d = daysUntilNext(birthdate.getMonth(), birthdate.getDate());

console.log(d   ' day'   (d > 1 ? 's' : '')   ' until yer birthday');