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JayCooper's avatar
JayCooper
Community Member
3 years ago

JavaScript to Subtract Days from Current Date

I'm working on a course that involves sorting juveniles with one of the criteria being their age.  I'm looking to display each child's age based on the current date, minus X number of days so that t...
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BrianBatt-86639's avatar
BrianBatt-86639
Community Member
3 years ago
Jay Cooper

I'm working on a course that involves sorting juveniles with one of the criteria being their age.  I'm looking to display each child's age based on the current date, minus X number of days so that the child's birthday the relative no matter when a learner takes the course.  

For example, I need a child that is a couple days short of 18 so I'm looking for JavaScript that will calculate the current date minus X number of days to produce a date of birth that would make the child a few days short of 18 (e.g., Feb 16, 2023 minus 6564 days).  

I've used JS in my projects before (I'm novice to low intermediate), but this one has me stumped.  

Thanks in advance for any help.

Jay

Hi Jay.  I haven't tested this, but this should give you some ideas:

const currentDate = new Date();
const dateOfBirth = new Date("2005-02-18");
const ageInMilliseconds = currentDate - dateOfBirth; // calculate the age in milliseconds by subtracting the date of birth from the current date
const eighteenYearsInMilliseconds = 18 * 365.25 * 24 * 60 * 60 * 1000; // calculate the number of milliseconds in 18 years, taking into account leap years
const dateOfEighteenthBirthday = new Date(dateOfBirth.getTime() + eighteenYearsInMilliseconds); // calculate the date of the child's 18th birthday by adding 18 years to the date of birth
console.log(dateOfEighteenthBirthday.toLocaleDateString()); // output date of 18th birthday in local date format