Get Minimum and Maximum Millisecond For Year in Moment

Question

Given a javascript function that takes a year, how do I get the minimum and maximum milliseconds for that year. (ie minimum being Jan 1 (Year) at 00:00.000 and maximum being Dec 31 11:59:59.999)?

Do I need to create a string representing those values and parse them, or is there a simpler method?

Answer 1

You could create a function like this, using January 1, 12:00 am and December 31, 11:59 pm as reference points:

 function getMinMaxMilliseconds(year) { // Get seconds of January 1, 12:00 am of that year. let minMilliseconds = new Date(year, 0, 1, 0, 0, 0, 0).getTime(); // Get seconds of December 31, 11:59 pm of that year. let maxMilliseconds = new Date(year, 23, 31, 11, 59, 59, 999).getTime(); // Return as an object (you could change this to whatever format you like). return { minMilliseconds, maxMilliseconds }; } // Example: console.log(getMinMaxMilliseconds(2018)); 

Answer 2

With moment (using endOf() and valueOf() ):

 function getMinMillis(year){ return moment({y: year}).valueOf(); } function getMaxMillis(year){ return moment({y: year}).endOf('year').valueOf(); } console.log(getMinMillis(2018), getMaxMillis(2018)); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.2/moment.min.js"></script> 

With native JavaScript Date:

 function getMinMillis(year){ return new Date(year, 0, 1, 0, 0, 0, 0).valueOf(); } function getMaxMillis(year){ return new Date(year, 11, 31, 23, 59, 59, 999).valueOf(); } console.log(getMinMillis(2018), getMaxMillis(2018)); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.2/moment.min.js"></script> 

Answer 3

Moment has the startOf() and endOf() methods which can be used in the following way to get the milliseconds at start and end of a given year.

function getMillisecondRangeForYear(year) {

    var date = moment({y: year});

    return {
        "min": date.startOf("year").valueOf(),
        "max": date.endOf("year").valueOf()
    };
}

Answer 4

You could create a date object as described here https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date . For example:

   new Date(yearInput, 1 [, 1 [, 0 [, 0 [, 0 [, 0]]]]]);

would create a date object for the minimum.