Subtract hours from date and time

Question

Could someone help me with this. I need to finish something for a schoolproject which we are displaying tonight and I have to subtract 2 hours from this code. Javascript is totally not my thing.

<a href="urltopage.php"><span id="datetime"></span></a>

<script>
var dt = new Date();
document.getElementById("datetime").innerHTML = dt.toLocaleString();
</script>

I have no idea how to change this. Thanks in advance.

Regards, Justin

What have you tried? I'm sure there are dozens of question on this site that have example of what you want. First result from a search is: [How do I subtract minutes from a date in javascript?](https://stackoverflow.com/questions/674721/how-do-i-subtract-minutes-from-a-date-in-javascript) Which could be modified to hours. — DBS, Aug 21 '20 at 14:34
let dt = new Date(Date.now() - 7200); 7200 = 60sec per minute * 60 minutes * 2. — Denis Giffeler, Aug 21 '20 at 14:39

score 5 · Answer 1 · answered Aug 21 '20 at 14:38

5

Try

var dt = new Date();
dt.setHours(dt.getHours() - 2);
document.getElementById("datetime").innerHTML = dt.toLocaleString();

Have a look here https://codepen.io/vyspiansky/pen/abNBqrx

answered Aug 21 '20 at 14:38

Ihor Vyspiansky

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you are my HERO! Thank you so much! Just one quick additional question. What if I would want to subtract 2 hours and 7 minutes? – Justin Forga Aug 21 '20 at 14:44
I guess, `dt.setMinutes(dt.getMinutes() - 7);` should help to achieve this goal. Demo - https://codepen.io/vyspiansky/pen/KKzNoPR – Ihor Vyspiansky Aug 21 '20 at 14:46
I tried that, but guess I had a typo because it didn't work. But now it does, stupid me. You are truly my hero and saved me from a lot of searching. Thanks so much! – Justin Forga Aug 21 '20 at 14:49

score -2 · Answer 2 · answered Aug 21 '20 at 14:34

-2

You can use moment.js.

moment(dt).subtract(2, 'hours').format();

answered Aug 21 '20 at 14:34

mkkekkonen

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Thanks for the quick reply. But like I said, I have no knowledge of Javascript. So how do I implement this in my current script? – Justin Forga Aug 21 '20 at 14:35
using `moment` is a good solution – assembler Aug 21 '20 at 14:37
2

Moment is a good library for handling time but I would argue it really isn't necessary for a one off date manipulation. – DBS Aug 21 '20 at 14:38
You can use a JS file that you can refer on the page via a CDN. I.e. `` – mkkekkonen Aug 21 '20 at 14:39
Moment is deprecated, do not use on new projects. – Cal Corbin Nov 03 '21 at 18:42

Subtract hours from date and time

2 Answers2