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The user is providing time in the format of 12:00:00 (which is in string), and I want to add 1 or 3 hours to the time and show it as the end time.

The code:

function showCart(cart) {
  
  for (var i = 0; i < cart.length; i++) {
    var slotHtmlTr = '';
    var c = i + 1;
    slotHtmlTr += '<tr style="border: 1px solid black;" id="slot'+c+'">';
    slotHtmlTr += '<td style="border: 1px solid black;">Slot '+c+'</td>';
    slotHtmlTr += '<td style="border: 1px solid black;">'+cart[i].from_date+'</td>';
    slotHtmlTr += '<td style="border: 1px solid black;">'+cart[i].start_time+'</td>';
    slotHtmlTr += '<td style="border: 1px solid black;">End Time here</td>';
    slotHtmlTr += '<td style="border: 1px solid black;">'+cart[i].room_id+'</td>';
    slotHtmlTr += '<td style="border: 1px solid black;">'+cart[i].duration+'</td>';
    var slotPrice = (cart[i].duration == "1") ? 15 : 30;
    slotHtmlTr += '<td style="border: 1px solid black;">'+slotPrice+ '</td>';
    slotHtmlTr += '</tr>';
  }
  $('#slotsDetails').append(slotHtmlTr);
  // console.log(slotHtml);
}

How I am adding the time:

let hrsAdd = 3;
let start_time = cart[i].start_time;
let end_time = new Date(start_time); //showing some error
console.log(end_time + hrsAdd);

I know I am doing something wrong, but can't figure out what?

Thanks in advance!

Sollyhub LLP
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  • Does this answer your question? [How to parse a time into a Date object from user input in JavaScript?](https://stackoverflow.com/questions/141348/how-to-parse-a-time-into-a-date-object-from-user-input-in-javascript) – Heretic Monkey Apr 07 '21 at 12:24
  • do not forget that time can move you to the next day (*adding 3 hours to 11pm should go to 2am, but in the next day. do you account for day changes ?*) – Gabriele Petrioli Apr 07 '21 at 12:29
  • @GabrielePetrioli No, not for day changes. only time. – Sollyhub LLP Apr 07 '21 at 12:34
  • @HereticMonkey No it does not. I tried but I want only time like 12:00:00 not GMT, date, and all. – Sollyhub LLP Apr 07 '21 at 12:55
  • Then why are you using `new Date(start_time)`? The `Date` object allows you to add hours to the datetime value, then format it as the time portion ([jquery: How to get hh:mm:ss from date object?](https://stackoverflow.com/q/19346405/215552)). – Heretic Monkey Apr 07 '21 at 13:00

1 Answers1

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You have to remember that Date class has some limitation on creating it, so you may not just set your time on the constructor, it must be in a specific format. For more details take a look on the JS Date class documentation.

Your time calculation can be done with a similar code to this:

srcTime = "12:01:02"; // value sent by the user
baseDateTime = new Date(); // the date does not matter to us, but it comes together as it is the Date class
[srcHour, srcMinute, srcSecond] = srcTime.split(":"); // we separate the value in the right variables
baseDateTime.setHours(parseInt(srcHour) + 3); // update the Date object with user hour + 3 hours

// from this point on you can work with the baseDateTime variable to extract the time, date and etc.
// for example:
end_time = baseDateTime.getHours() + ":" + baseDateTime.getMinutes() + ":" + baseDateTime.getSeconds();
Marcel Kohls
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