Add 6 hours to current time and display to page

Question

So, I'm trying to add some labels to a graph, and I want to add them to 6, 12, 18, and 24 hours on the horizontal axis.

I want to write these times in a "hh:mm" format (23:10, 05:10, 11:10, and 17:10 for example) for the local (computer) timezone?

Can someone help me with this?

https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Date — jbabey, Oct 23 '12 at 15:38
If your problem is the formatting see my answer http://stackoverflow.com/questions/10645994/node-js-how-to-format-a-date-string-in-utc/10647272#10647272 — HBP, Oct 23 '12 at 15:49

score 41 · Accepted Answer · edited May 23 '17 at 12:09

41

based on How to add 30 minutes to a JavaScript Date object?

var d1 = new Date ();
var d2 = new Date ( d1 );
d2.setHours ( d1.getHours() + 6 );

https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Date will show how to manipulate Date objects.

added your code with some fixes. edited to add second document.write

<script type="text/javascript"> 
var timer = 24; 
var d1 = new Date(); 
var d2 = new Date();
d1.setHours(+d2.getHours()+(timer/4) ); 
d1.setMinutes(new Date().getMinutes()); 
document.write(d1.toTimeString("hh:mm"));
document.write(d1.getHours()+":"+d1.getMinutes());
</script>

edited May 23 '17 at 12:09

Community

1
1

answered Oct 23 '12 at 15:40

Pedro del Sol

2,840
9
39
52

When I use this, I get an uncaught exception. Here's my code: – A_Elric Oct 23 '12 at 16:23
when i copied your code there was a strange character after the last semi-colon. also, where are you defining `now`? did you mean [Date.now()](http://msdn.microsoft.com/en-us/library/ff679974%28v=vs.94%29.aspx) because that returns the number of milliseconds since the epoch. – Pedro del Sol Oct 23 '12 at 16:29
As a final question, the output of that string is: 18:45:12 GMT-0400 (Eastern Daylight Time) how do I get rid of everything after the 18:45? – A_Elric Oct 23 '12 at 16:46
2

`document.write(d1.getHours()+":"+d1.getMinutes());` – Pedro del Sol Oct 23 '12 at 16:49
There's an error in your code. it should be var d1 = new Date (), d2 = new Date ( d1 ); You can't define a var after a comma. – Michel May 15 '16 at 09:30

score 9 · Answer 2 · answered Oct 23 '12 at 15:51

9

try this

var today = new Date();
alert(today);
today.setHours(today.getHours()+6);
alert(today);
today.setHours(today.getHours()+6);
alert(today);
today.setHours(today.getHours()+6);
alert(today);
today.setHours(today.getHours()+6);
alert(today);

answered Oct 23 '12 at 15:51

Ramesh Kotha

8,266
17
66
90

So... this works with alerts, but not with document.write, why would that be? – A_Elric Oct 23 '12 at 15:55
i didn't try with document.write. – Ramesh Kotha Oct 23 '12 at 17:37

score 4 · Answer 3 · answered Oct 23 '12 at 15:44

var MILLISECS_PER_HOUR = 60 /* min/hour */ * 60 /* sec/min */ * 1000 /* ms/s */;

function sixHoursLater(d) {
  return new Date(+d + 6*MILLISECS_PER_HOUR);
}

The numeric value of a date is milliseconds per epoch, so you can just add a number of milliseconds to it to get an updated numeric value.

The + prefix operator converts the date to its numeric value.

score 2 · Answer 4 · answered Oct 23 '12 at 15:51

Does this help?

function getDateString(addT){
    var time = new Date();
    time.setHours(time.getHours() + addT );
    return ((time.getHours()<10)?"0":"")+time.getHours() + ':' + time.getMinutes();
}

Then just use it pop out the data on the graph where you want?

ie:

for (i=0;i<=24;i+=6){
    yourbox.innerHTML = '<p>'+getDateString(i)+'</p>'; 
}

or somesuch;

score 2 · Answer 5 · answered Jan 03 '18 at 08:17

2

I like to do this like that

new Date(new Date().setHours(new Date().getHours() + 6))

or

new Date(new Date().setHours(new Date().getHours() + 6)).toString()

answered Jan 03 '18 at 08:17

Alan Aasmaa

56
5

Add 6 hours to current time and display to page

5 Answers5

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