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display diffrent images depending on time

So I have a sort of homepage with some code to change the background based on the time. My problem is: it only checks the time when the page first loads, I need it to be constantly checking for it. Here is my code, please help.
var today2 = new Date();
var h2 = today2.getHours();
if (h2 > 18) {
document.body.style.backgroundImage = "url('cityatnight2.jpg')";
}
else if (h2 < 9) {
document.body.style.backgroundImage = "url('sunrise2.jpg')";
}
else {
document.body.style.backgroundImage = "url('homescreen3.jpg')";
}

I would suggest using the setInterval command. It allows you to specify that code run at a given interval. For example, to run every hour, you could do this:
function SetBackground()
{
var today2 = new Date();
var h2 = today2.getHours();
if (h2 > 18) {
document.body.style.backgroundImage = "url('cityatnight2.jpg')";
}
else if (h2 < 9) {
document.body.style.backgroundImage = "url('sunrise2.jpg')";
}
else {
document.body.style.backgroundImage = "url('homescreen3.jpg')";
}
}
// 1 Hour Interval
window.setInterval(SetBackground, 60 * 60 * 1000);
Read more about that function here: https://www.w3schools.com/jsref/met_win_setinterval.asp

Try this code.
var changeBg = function(num){
if (num > 18) {
document.body.style.backgroundColor = "red";
}
else if (num < 9) {
document.body.style.backgroundColor = "blue";
}
else {
document.body.style.backgroundColor = "black";
}
}
setInterval(function(){
var today2 = new Date();
var h2 = today2.getSeconds(); //edit here. sec -> hour.
console.log(h2)
changeBg(h2);
},1000) //and edit here. 1000 means 1sec

Timer doesn't start running

I tried to make a normal Timer in Javascript and started coding something with help of some Tutorials.
I did it the same way as in the tutorial but my timer actually doesn't start running, and i don't know why.
Here is my Code:
var time = 0;
var running = 0;
function startPause() {
if(running == 0){
running = 1;
increment();
}
else{
running = 0;
}
}
function reset(){
running = 0;
time = 0;
document.getElementById("startPause").innerHTML = "Start";
}
function increment() {
if(running == 1){
setTimeout(function(){
time++;
var mins = Math.floor(time / 10 / 60);
var secs = Math.floor(time / 10);
var tenths = time % 10;
document.getElementById("output").innerHTML = mins + ":" + secs + ":" + tenths;
}, 100);
}
}
</script>
i also made a fiddle you can check out here: https://jsfiddle.net/adamswebspace/5p1qgsz9/
what is wrong with my code?

I cleared a bit your code, and used setInterval instead of setTimeOut;
note that you have to use clearInterval in order to stop the timer
var time = 0;
var running = 0;
var timer = null;
function increment() {
time++;
var mins = Math.floor(time / 10 / 60);
var secs = Math.floor(time / 10);
var tenths = time % 10;
document.getElementById("output").innerHTML = mins + ":" + secs + ":" + tenths;
}
function startPause() {
if (running === 0) {
running = 1;
timer = setInterval(increment, 1000);
} else {
running = 0;
clearInterval(timer);
}
}
function reset() {
running = 0;
time = 0;
document.getElementById("startPause").innerHTML = "Start";
}

you have to bind the function like the following
var vm = this;
vm.startPause = function startPause() {
if (running == 0) {
running = 1;
vm.increment();
} else {
running = 0;
}
}
https://jsfiddle.net/f7hmbox7/

In order for onclick to find the function in your code. It must be supplied in a <script> tag for JSFiddle.
You can just add
<script>
/** JS Here */
</script>
and it will work.
Keep in mind that all the errors coming from JS are showed in the console of your browser inspector.
https://jsfiddle.net/dzskncpw/

JavaScript function working in IE not in chrome

I am facing problem while enabling & disabling the div block in web page. I need to display dvMessage block in non-working hours and dvChat in working hours.
For this I have written a code CheckTime as follows:
function CheckTime() {
var hours = currentTime.getHours()
var minutes = currentTime.getMinutes()
var time = hours + ":" + minutes
var isweekend = currentTime.getDay();
if ((time >= "20:00" && time <= "8:00")) {
document.getElementById("dvMessage").style.display = "block";
document.getElementById("dvChat").style.display = "none";
}
else {
document.getElementById("dvMessage").style.display = "none";
document.getElementById("dvChat").style.display = "block";
//End
}
}
Calling this function at body onload="CheckTime(); div id="dvChat" and div id="dvMessage" style="display: none;" class="message"
But this function works in IE but not in chrome. Is there anything else I need to do for Crome?
Thanks in advance.

Thanks, It works after currentTime is defined and adding missing Semicolons.
function CheckTime() {
var currentTime = new Date();
var hours = currentTime.getHours();
var minutes = currentTime.getMinutes();
var time = hours + ":" + minutes;
var isweekend = currentTime.getDay();
if ((time >= "20:00" && time <= "9:00")) {
document.getElementById("dvMessage").style.display = "block";
document.getElementById("dvChat").style.display = "none";
}
else {
document.getElementById("dvMessage").style.display = "none";
document.getElementById("dvChat").style.display = "block";
//End
}
}

Countdown timer javascript mins into hours

I'm a beginner in JavaScript, I wrote a countdown timer, but I don't know how to convert the mins into hours. I think its not to hard, but I can't do it, whenever I wrote new rows its not working. Here is my code:
var minutesRemaining;
var secondsRemaining;
var intervalHandle;
function resetPage() {
document.getElementById('inputArea').style.display = 'block';
//hide pause button by default
document.getElementById("pauseArea").style.display = "none";
//hide resume button
document.getElementById("resumeArea").style.display = "none";
}
function resumeCountdown() {
tick();
intervalHandle = setInterval(tick, 1000);
//hide resume button when resuming
document.getElementById("resumeArea").style.display = "none";
//show resume button;
document.getElementById("pauseArea").style.display = "block";
return;
}
function pauseCountdown() {
clearInterval(intervalHandle);
document.getElementById("pauseArea").style.display = "none";
document.getElementById("resumeArea").style.display = "block";
return;
}
function tick() {
//grab h1
var timeDisplay = document.getElementById('time');
//turn seconds into mm:55
var min = Math.floor(secondsRemaining / 60);
var sec = secondsRemaining - (min * 60);
//add leading 0 if seconds less than 10
if (sec < 10) {
sec = '0' + sec;
}
//concatenate with colon
var message = min.toString() + ':' + sec;
// now change the display
timeDisplay.innerHTML = message;
//stop if down to zero
if (secondsRemaining === 0) {
alert('Done!');
clearInterval(intervalHandle);
resetPage();
}
// subtract from seconds remaining
secondsRemaining--;
}
function startCountdown() {
//get contents
var minutes = document.getElementById('minutes').value;
//check if not a number
if (isNaN(minutes)) {
alert("Please enter a number!");
return;
}
//how many seconds?
secondsRemaining = minutes * 60;
//call tick
intervalHandle = setInterval(tick, 1000);
//hide form
document.getElementById('inputArea').style.display = 'none';
//show pause when running
document.getElementById("pauseArea").style.display = "block";
}
window.onload = function () {
// create text input
var inputMinutes = document.createElement('input');
inputMinutes.setAttribute('id', 'minutes');
inputMinutes.setAttribute('type', 'text');
inputMinutes.setAttribute('placeholder', 'Idő megadása');
//pause button
var pauseButton = document.getElementById("pauseBtn");
pauseButton.onclick = function() {
pauseCountdown();
};
//resume button
var resumeButton = document.getElementById("resumeBtn");
resumeButton.onclick = function() {
resumeCountdown();
};
//create button
var startButton = document.createElement('input');
startButton.setAttribute('type', 'button');
startButton.setAttribute('value', 'Indítás');
startButton.onclick = function () {
startCountdown();
};
// add to DOM
document.getElementById('inputArea').appendChild(inputMinutes);
document.getElementById('inputArea').appendChild(startButton);
document.getElementById("pauseArea").appendChild(pauseButton);
document.getElementById("resumeArea").appendChild(resumeButton);
//hide pause button by default
document.getElementById("pauseArea").style.display = "none";
//hide pause button by default
document.getElementById("resumeArea").style.display = "none";
};

Here is what i just wrote really quick. It may help you. But you can just do some basic math to get your conversions and handle the remainder. Like so:
function countDown(future_date_in_millis) {
var date = new Date();
var current_time = date.getTime();
//get the future date and time
var future_date = future_date_in_millis.getTime(); //1438077258047; //date.getTime();
// get the duration in milliseconds
// 1 day = 86400000 millis
var duration = future_date - current_time;
var dd = Math.floor(duration / 86400000);
var remainder = duration % 86400000;
var hh = Math.floor(remainder / 3600000);
remainder = remainder % 3600000;
var mm = Math.floor(remainder / 60000);
remainder = remainder % 60000;
var ss = Math.floor(remainder / 1000);
var days = document.getElementById("dd");
var hours = document.getElementById("hh");
var minutes = document.getElementById("mm");
var seconds = document.getElementById("ss");
days.innerHTML = dd.toString();
hours.innerHTML = hh.toString();
minutes.innerHTML = mm.toString();
seconds.innerHTML = ss.toString();
}
window.setInterval(function () {
/// call your function here
var d = new Date("July 15, 2015 4:52:00 PM");
countDown(d);
}, 1000);

Forcing page refresh at a specific time with timezone

I'm trying to force a page to refresh with js at a specific time, after digging around I found the script below. However, it doesn't appear to take into consideration timezones. How would I implement that?
<html>
<head>
<title></title>
<script type="text/javascript">
function refreshAt(hours, minutes, seconds) {
var now = new Date();
var then = new Date();
if(now.getHours() > hours ||
(now.getHours() == hours && now.getMinutes() > minutes) ||
now.getHours() == hours && now.getMinutes() == minutes && now.getSeconds() >= seconds) {
then.setDate(now.getDate() + 1);
}
then.setHours(hours);
then.setMinutes(minutes);
then.setSeconds(seconds);
var timeout = (then.getTime() - now.getTime());
setTimeout(function() { window.location.reload(true); }, timeout);
}
refreshAt(15,06,0); //Will refresh the page at 3:06pm
</script>
</head>
<body onLoad="setInterval('getCurrentTime()', 1000);">
<div id="time"></div>
content
</body>
</html>

Here you go, reload will occur for every user exactly as you define in global vars in script:
EDIT!!! I had bug in code so I have updated the script...
EDIT working example:
http://simplestudio.rs/yard/tinediffredir/content.html
<html>
<head>
<title>Chk diff and reload if match</title>
<script>
var reload_time = "15060"; // this is 15:06:00 - change to desired reload time
var reload_hour_diff = 15; // for cheking diff - change to desired hours
var reload_minute_diff = 6; // for cheking diff - change to desired minutes
var time_zone_offset = "-5"; // globally looking from GMT time, change this according to DST
var reload_time_checker = setInterval(function(){reload_page()},300);
var diff = null;
function chk_reload_moment(offset) {
dat = new Date();
utc = dat.getTime() + (dat.getTimezoneOffset() * 60000);
default_date = new Date(utc + (3600000*offset));
var default_year = default_date.getFullYear();
var default_month = default_date.getMonth();
var default_day = default_date.getDate();
var default_hour = default_date.getHours();
var default_minutes = default_date.getMinutes();
var default_seconds = default_date.getSeconds();
user_date = new Date();
var user_year = user_date.getFullYear();
var user_month = user_date.getMonth();
var user_day = user_date.getDate();
var user_hour = user_date.getHours();
var user_minutes = user_date.getMinutes();
var user_seconds = user_date.getSeconds();
user_current = user_hour+""+user_minutes+""+user_seconds;
default_current_f = default_day+"/"+default_month+"/"+default_year+" "+default_hour+":"+default_minutes+":"+default_seconds;
user_current_f = user_day+"/"+user_month+"/"+user_year+" "+user_hour+":"+user_minutes+":"+user_seconds;
var timeEnd = new Date(user_current_f);
var timeEndH = timeEnd.getHours();
var timeEndM = timeEnd.getMinutes();
var new_reload_minute_diff = 60+reload_minute_diff;
diff = (timeEndH - reload_hour_diff + 12) + " hours " + (new_reload_minute_diff - timeEndM) + " minutes";
if (user_current == reload_time) {
return true;
}
else {
return false;
}
}
function reload_page() {
var chktime = chk_reload_moment(time_zone_offset);
if (chktime) {
window.location.reload();
}
else {
var timer_div = document.getElementById('timer');
timer_div.innerHTML = "remaining: " + diff + " until new content";
}
}
</script>
</head>
<body>
<div id="timer">
</div>
</body>
</html>
I think it is clear how to configure it but if you have some problems feel free to ask...