Script to change image at same time every day

[davidwhite]

Hello,

I need a script (must be in JavaScript) that changes an image at the same time every day of the week.

Let's say it changes at 8am every day.

I presume it would hold the 7 images in an array and would use something like Date.UTC to ensure everyone was seeing the same image? (Assuming people have their times set right).

Is this something that's hard to do? I have tried to modify existing scripts but can't get anything to work.

Any help appreciated.

Thanks

[Philip M]

Yes, terribly hard.

<img id = "myimage" src = "">

<script type = "text/javascript">

// change image at 0800 daily according to user's time

var pics = [];
pics[0] = "Sunday.jpg";
pics[1] = "Monday.jpg";
pics[2] = "Tuesday.jpg";
pics[3] = "Wednesday.jpg";
pics[4] = "Thursday.jpg";
pics[5] = "Friday.jpg";
pics[6] = "Saturday.jpg"

var d = new Date();   // today
var hr = 8;  // hours to subtract (or add)
d = d.getTime() - (3600000*hr);  // subtract hr hours
var nd = new Date(d);
var dy = nd.getDay();
document.getElementById("myimage").src = pics[dy];

</script>

You say you want all users to see the same image, changing at 0800 local time. Obviously that is not the same thing as all users seeing the same image at all times. Or do you want to change the image at 0800 GMT, regardless of the user's local time?


It wasn't funny but it did make me laugh. - Reporter, Surrey Advertiser.

[davidwhite]

Originally Posted by Philip M

Yes, terribly hard.

<img id = "myimage" src = "">

<script type = "text/javascript">

// change image at 0800 daily according to user's time

var pics = [];
pics[0] = "Sunday.jpg";
pics[1] = "Monday.jpg";
pics[2] = "Tuesday.jpg";
pics[3] = "Wednesday.jpg";
pics[4] = "Thursday.jpg";
pics[5] = "Friday.jpg";
pics[6] = "Saturday.jpg"

var d = new Date();   // today
var hr = 8;  // hours to subtract (or add)
d = d.getTime() - (3600000*hr);  // subtract hr hours
var nd = new Date(d);
var dy = nd.getDay();
document.getElementById("myimage").src = pics[dy];

</script>

You say you want all users to see the same image, changing at 0800 local time. Obviously that is not the same thing as all users seeing the same image at all times. Or do you want to change the image at 0800 GMT, regardless of the user's local time?


It wasn't funny but it did make me laugh. - Reporter, Surrey Advertiser.

Thanks for the help.

To be honest, thinking about it, it's not that big a deal that people are in different time zones. So long as it changes once a day for everyone then that's fine.

Let's just keep it simple and assume it changes 8.00am UTC for everyone, no matter what their local time is.

[Philip M]

Originally Posted by davidwhite

Let's just keep it simple and assume it changes 8.00am UTC for everyone, no matter what their local time is.

It would seem to be better to change at 0800 local time for everyone, but if for some reason every user must see the same image (why?) then why change at 0800 rather than midnight UTC?

<img id = "myimage" src = "">

<script type = "text/javascript">

// change image at 0800 UTC daily

var pics = [];
pics[0] = "Sunday.jpg";
pics[1] = "Monday.jpg";
pics[2] = "Tuesday.jpg";
pics[3] = "Wednesday.jpg";
pics[4] = "Thursday.jpg";
pics[5] = "Friday.jpg";
pics[6] = "Saturday.jpg"

var d = new Date(); // today
var hr = 8; // hours to subtract (or add)
var off = d.getTimezoneOffset(); // offset in minutes
off = off *60*1000; // offset in milliseconds
d = d.getTime() - (3600000*hr) - off; // subtract hr hours and timezone offset
var nd = new Date(d);
var dy = nd.getDay();
document.getElementById("myimage").src = pics[dy];

</script>

Note that Javascript relies on the accuracy of the user's computer clock. If it is important that all users always see the same image then you need server-side scripting.