So here's what I'm trying to do - I have the following code:
<div id="on">
<p>We are: <span class="onair"><a href="#">ON AIR</a></span></p>
</div>
<div id="off">
<p>We are: <span class="offair"><a href="#">OFF AIR</a></span></p>
</div>
And what I'd like to do is "show" the "on" div on Tuesday's from 3pm to 4pm (server time), while simultaneously hiding the "off" div - and then switch that around for every other date/time.
?
If you use PHP you can do logic statements on the server-side to render the exact information you need instead of calculating it later on the client side.
(Client side solutions work too if you dont care about where the time is coming from)
(1) You can have the server render javascript for you that you can use in a script
//if you want the server's time you can do this:
<?php $timestamp = time(); ?>
//render variables in javascript instead of html
<?php
echo <<<EOD
<script>
var timestamp = ${timestamp}
//then later in your javascript process the timestamp logic to update the dom
</script>
EOD;
?>
(2) You can also have the server render a className in the body tag based on whether or not a condition is true or false. (This is my preferred method usually)
//onAirClass( min, max, timestamp ) returns className
//this function returns onair or offair class if the timestamp is in range
function onAirClass( timeMin, timeMax, timestamp ){
if( timestamp >= timeMin && timestamp <= timeMax ){
return 'onair';
}
return 'offair'
}
//using onAirClass( min, max, timestamp )
<?php $bodyClass = $bodyClass . ' ' . onAirClass( $timestamp ); ?>
<?php echo "<body class='${bodyClass}'>"; ?>
then in your styles you can have the elements you want to hide or show based on class inheritance from the body tag.
Check out the PHP time function to create new time strings, and do time calculations for your onAirClass() function
How to check the time between a given time range
UPDATED
Corrected PHP syntax errors
@maerics solution is OK, depending on what you want to do, just don't EVER do anything like this:
var timestamp = $('#server-timestamp').text();
Ultimately, there are many ways to do the same thing, but some things are more 'right' than others.
There are reasons to do some calculations on the client side vs the server side, and vice versa. As a newbie developer, just make sure that whatever method you use:
Have the server provide a timestamp when it generates the page and have the client also generate a timestamp when it loads the page so that you can calculate the time offset between the two systems.
Then you can call a function on some interval that checks the current server time to see if it is within the 3pm-4pm period and show/hide the target elements as needed.
From the server:
<div id="server-timestamp" style="display:none">2013-02-12T18:01:19Z</div>
On the client:
$(document).on('load', function() {
var serverTime = new Date($('#server-timestamp').text())
, clientTime = new Date()
, offsetMilliseconds = (clientTime - serverTime);
setInterval(function() {
// If server time is 3pm-4pm then hide/show divs...
}, 1000 /* every second */);
});
Actually this can be accomplished using just JavaScript without any server-side code, by using your timezone offset.
Here's a function you can use:
var onAir = function (day, start, end, timezone) {
var local, utc, show, days, onAir, startValues, endValues, startTime, endTime, startMinutes, endMinutes, showMinutes;
// by default, we are not on air
onAir = false;
// map day numbers to indexes
days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Firday', 'Saturday'];
// convert start/end times to date objects
startValues = start.split(':');
endValues = end.split(':');
startTime = new Date();
endTime = new Date();
startTime.setHours(startValues[0], startValues[1]);
endTime.setHours(endValues[0], endValues[1]);
// add the hours minutes together to get total minutes
startMinutes = (startTime.getHours() * 60) + startTime.getMinutes();
endMinutes = (endTime.getHours() * 60) + endTime.getMinutes();
// get the current local time
local = new Date();
// get the current time in the show's timezone
utc = local.getTime() + (local.getTimezoneOffset() * 60000);
show = new Date(utc + (3600000*timezone));
// convert the show hours + minutes to just minutes
showMinutes = (show.getHours() * 60) + show.getMinutes();
// test to see if the show is going on right now
if (days[show.getDay()] === day && (showMinutes >= startMinutes && showMinutes <= endMinutes)) {
onAir = true;
}
return onAir;
}
// example: Air time is Tuesday between 1-2pm Central Time (-6)
var texasShowOnAir = onAir('Tuesday', '13:00', '14:00', '-6'));
// now check if we are on air
if (texasShowOnAir) {
// do stuff here...
}
You can now use this function like this:
var check = onAir('DAY', 'STARTTIME', 'ENDTIME', 'YOURTIMEZONE');
This will return a true/false. Be sure and use 24 hour format.
I would even argue that this is better than using your server's timestamp, because often (especially if you have shared hosting), your server can be set in a different timezone than you.
Here's a demo fiddle: http://jsfiddle.net/stevenschobert/mv54B/
