Create an array with time intervals and add 2 hours

Question

I need to create an array of elements in javascript, which add 2 hours to a certain time I set. I give an example. The time is

14:00.

I need, to create an array that contains all 30 minute intervals up to 16:00.
Ex

14:00
14:30
15:00
15:30

Answer 1

Here is a function that produces the time specifications as strings. It can take an optional second argument to specify the end-time (16:00 in your question).

Two utility functions convert a time string to (and from) a number of minutes.

Finally, the result array is created with Array.from:

const toMinutes = str => str.split(":").reduce((h, m) => h * 60 + +m);

const toString = min => (Math.floor(min / 60) + ":" + (min % 60))
                       .replace(/\b\d\b/, "0$&");

function slots(startStr, endStr="16:00") {
    let start = toMinutes(startStr); 
    let end = toMinutes(endStr);
    return Array.from({length: Math.floor((end - start) / 30) + 1}, (_, i) =>
        toString(start + i * 30)
    );
}

console.log(slots("14:00"));