Convert 12 hour (AM/PM) string to 24 Date object using moment js

I have a output resulting from a timepicker giving 12 hour format of time.

Eg : "1:45 AM (or) "12:15 PM" as **string**

Is there a way to parse this string format to 24 hour using moment js back to date object?

See documentation of moment js parse function

JSFiddle

var dt = moment("12:15 AM", ["h:mm A"]).format("HH:mm");

I know that this answer is not for the question (actually it is for the opposite case), but I will put it for completeness and if someone (like me) was looking for it.
In case you want to convert from the 24 Hour system to 12 Hour system then you could use the following

return moment("13", ["HH"]).format("hh A");

the previous code will produce the result 1 PM

Just a little conversation "2 PM" to "14.00"

const number = moment("02:00 PM", ["h:mm A"]).format("HH:mm");
console.log(number); // Output = "14.00"

"14.00" to "2 PM"

const number = moment("14.00", ["HH.mm"]).format("hh:mm a");
console.log(number); // Output = "02:00 pm"

var today = new Date();
let options = {  
    hour: "2-digit", minute: "2-digit"  
};  
console.log(today.toLocaleTimeString("en-us", options));

In full calender to show time in 12 hour format like 01:00 PM i used following format - timeFormat: 'hh:mm A'. "timeFormat" is the property of events of fullcalender.

Same format 'hh:mm A' we can use to format datetime object using momentjs.

moment("145","hmm").format("HH:mm");

this would result in 01:45

using HH:mm will convert 12 hrs format to 24hrs while using hh:mm will convert 12hrs format

moment("12:15 PM").format("HH:mm")

you can use dayjs

return dayjs(date as string).format('DD/MM/YYYY HH:mm')

you will have :

03/03/2021 16:36

for more information, you can refer to https://day.js.org/docs/en/display/format

Here's how you can set the time of a Date object using a time String.

const date = new Date('1/1/21');
const pm = '2:30 PM';
const am = '11:00 AM';
const noon = '12:00 PM';
const midnight = '12:00 AM';

const mergeDateTime = (date, time) => {
  const parsedTime = moment(time, ['h:mm A']);
  const merged = moment(date).set({
    hours: parsedTime.get('hours'),
    minutes: parsedTime.get('minutes')
  });
  
  return merged.toDate();
};

const resultsList = document.querySelector('#results');

const inputs = [pm, am, noon, midnight];

inputs.forEach((input) => {
  const li = document.createElement('li');
  li.innerText = `${input} ➡ ${mergeDateTime(date, input)}`;
  resultsList.appendChild(li);
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js"></script>

<h3>Results</h3>
<ul id=results />