Check if half of a period has passed

Question

I have a system where the user can choose a period where after this period he earns for example + 2% of the sum he has chosen. If he tries to make an action with this sum before the half of the period it loses a percentage of its value. So what I want to know is how to calculate half of a date.

In my example:

I have for example in a mysql table the date when he put the sum and the date when the defined period will be finished. So if it is 24-2-2022 and he chooses in 6 months, there will be two pieces of information in the database 24-2-2022 and 24-8-2022. What I've done so far is split() the date to separate day, month and year. But here I am stuck because I do not know how to compare all this to see if the period is halfway or not.

Answer 1

You can write a function. But first you must convert your string to a valid date string. then you can use the Date Object.

d1 = "24-2-2022"
d2 = "24-8-2022"


function getDays(d1, d2) {
  _d1 = d1.split('-');
  _d2 = d2.split('-');


  date_1 = new Date(_d1[2] + '-' + _d1[1] + '-' + _d1[0])
  date_2 = new Date(_d2[2] + '-' + _d2[1] + '-' + _d2[0])

  return Math.floor((date_2 - date_1) / (1000*60*60*24));
}

console.log(getDays(d1, d2) + " days")  

Answer 2

You could use the day, month and year values to compare if the difference between the start day and today is bigger than half of the difference between the start and the end day :

let startDate = new Date(2022,1,24); //months are 0-indexed
let endDate = new Date(2022,7,24);
let halfDif = (endDate - startDate) / 2;
//new Date() => today
let isTodayAtLeastHalfway = new Date() - startDate >= halfDif;