Develop Reference

How to display Current time of Dallas and australia

I'm trying to display current time of Dallas and Australia and I have come up with the Code,but it's not working . I'm completely new to Java script and Java here is my code , please help me out in achieving this
<script>
var now = new Date();
var now_utc = now.getUTCHours()-6+":"+ now.getUTCMinutes()+":"+ now.getUTCSeconds()
document.getElementById("inner1").innerHTML+=now_utc;
var aus= new Date();
var aus_time= aus.getUTCHours()+11
document.getElementById("inner2").innerHTML+=aus_time;
</script>
I want to display Current time of Dallas,London,Australia.
Thanks you all.

As once was pointed out by an Apple Engineer: never ever do calendar calculations by yourself. There are tons of small and large pitfalls that most people are unaware of and thus are not taking into account.
If you need an accurate depiction of the (current) time in another Timezone there is no other way then use a library that has all the information regarding Timezones and its peculiarities.
If you do not care about being exact every day of the year then this might be overkill but you have to decide for yourself.
For Javascript there exists the https://github.com/mde/timezone-js library, which itself uses the Olsen Database (https://en.wikipedia.org/wiki/Tz_database).
You have to download the Timezone-Infos and provide them along your source code. Then you can do all that TZ-related calculations/
// 'now' in the Timezone of Chicago (Central Time, should be equal to that of Dallas)
var dt_chicago = new timezoneJS.Date('America/Chicago');
// 'now' in London
var dt_london = new timezoneJS.Date('Europe/London');
// 'now' in Brisbane - you should look up which timezones
// there are in Australia and which you want to display
var dt_brisbane = new timezoneJS.Date('Australia/Brisbane');
I just found out that there is another library http://momentjs.com/timezone/ but I have not used it yet so I may not recommend or advise against using it.

The below piece of code will calculate the current time of any specific time zone. Just pass the time zone of any specific country it will show the current time.
function calcTime(city, offset) {
var d = new Date();
var utc = d.getTime() - (d.getTimezoneOffset() * 60000);
var nd = new Date(utc + (3600000*offset));
return "The local time for city"+ city +" is "+ nd.toLocaleString();
}
console.log(calcTime('Dhaka', '+6.0')));
console.log(calcTime('Australia', '+11.0')));

You use now variable break your script.On live var aus_time you forget semicolon at this line.
As #Traktor53 said in comment AU have multiple timezone.
Your code is OS dependent you will check after change your system time.you will get wrong time. Its better way to use google time API.
function gettz(){
var dnow = new Date();
var dnow_utc = dnow.getUTCHours()-6+":"+ dnow.getUTCMinutes()+":"+ dnow.getUTCSeconds()
document.getElementById("inner1").innerHTML+=dnow_utc;
var aus= new Date();
var aus_time= aus.getUTCHours()+11;
document.getElementById("inner2").innerHTML+=(aus_time);
return;
}
</script>

Recurring function to reset variable/counter at midnight (moment.js, node.js)

I want to reset a variable during midnight. Every night.
I'm trying to build this function with Moment.js for Node but I can't seem to get the recurring part to work properly.
This is what I got so far.
// Calculate time to midnight
function timeToMidnight(){
var midnight = new Date();
midnight.setHours(0,0,0,0);
var now = new Date();
var msToMidnight = midnight - now;
console.log(' it is ' + msToMidnight + 'ms until midnight');
return msToMidnight;
};
// Reset counter at midnight
setTimeout(function(){
console.log("midnight, do something");
}, timeToMidnight());
How can I best make it recurring at midnight, every night?
Thanks in advance.

If you're using moment, consider instead this implementation
var moment = require('moment');
function timeToMidnight() {
var now = new Date();
var end = moment().endOf("day");
return end - now + 1000;
}
Like your function, this takes now milliseconds and calculates the number of milliseconds until midnight, but this is supported directly when using moment, which is nice. Add 1 extra second (1000 milliseconds) to get to the next day.
A typical pattern is for a function to call itself after a timeout.
function roundMidnight() {
console.log('at midnight');
setTimeout(roundMidnight,timeToMidnight());
}
setTimeout(roundMidnight,timeToMidnight());
Pretty generic, in fact depending on the value returned, you could schedule anything anytime, pretty useful, seem like someone must have thought of that.
node-schedule
A cron-like and not-cron-like job scheduler for Node.
And they did. Maybe what you really want is node-schedule. It looks like it's not really actively developed now, though.

How to make a loop do something during a certain time frame in JS

I'm pretty new to JavaScript so please keep that in mind when answering my question.
I'm trying to make something where it asks the user questions during a certain time frame. Questions are asked using the window.prompt() method. I have a do while loop going on in a function called askquestions() as you can see:
var randomNo1;
var randomNo2;
var time;
do {
randomNo1 = Math.random() * 9;
randomNo1 = Math.round(randomNo1);
randomNo2 = Math.random() * 9;
randomNo2 = Math.round(randomNo2);
window.prompt("What is " + randomNo1 + " + " + randomNo2 + "?")
} while (time == 0);
How can I make it that time = 1 after 30 seconds?
Thanks in advance for your help.

You can use:
document.setTimeout("str js code/func name call",millisec);
document.setTimeout("time=1;",30000);
to execute some js code once with delay
And for your specification the following method may be needed for other timing purposes:
document.setInterval("js code /func name call",millisec);
to execute at an interval
Besides,it is strongly not recommended to have a "waiting while" in your js code to provide some timing service, which may cause browser to take this thread as a not-responding thread

You could get the milliseconds since Jan 1 1970 using
date = new Date();
mil = date.getTime();
You do that at the beginning of your code for comparison, then get a more current one in the loop. If the time between the two is greater than some number of milliseconds, you can exit the loop (while(curDate.getTime()-mil<30000) would be 30 seconds)

javascript - time counter since start date and time

I have a new business, where I just hired someone to work for me, I am trying to make it easy for her to track her time, so I created a clock in button, that creates a record in a database, I have it pop up a small window, that she can click to clockout when she is done working.
I want it to show her on that popup window a counter that will show how long she has been working, so I want to create a javascript or jQuery that will start at a certain time and count from there. She is on the East Coast, our company is in the Central Timezone, so 1 hour behind her.
How can I get a javascript to start from a certain time and keep updating the timer, so she can see something like this:
[You've been working for: 01:01:01 HH::MM::SS] - and it is actively updating, climbing up.
All the timers I've found are not about time itself, but about starting at a time and counting down, or starting at 0 and counting up.
Is there a way to tell it a start time, so that way if she reloads the page, it does not start from 0, but will start at the time she clocked in, then add the time since and start from there?
I know it can be done, but I'm more of a Perl guy than a Javascript guy. I'm doing this on Wordpress, so I could use PHP and just tell her to refresh the page to see the current amount of time and then have it on page load show the current amount of time, but I think having a counter would be better and make it easier for her.
is there some code already done that I could modify myself to make it work? I cannot find any, anywhere. I'm willing to do all the work, I'm not asking for someone to do it for me.
I found this example someone did:
function get_uptime() {
var t1 = new Date()
var t2 = new Date()
var dif = t1.getTime() - t2.getTime()
seconds = dif / 1000;
Seconds_Between_Dates = Math.abs(seconds);
document.getElementById("seconds").innerHTML = Seconds_Between_Dates;
setTimeout(get_uptime, 1000);
}
get_uptime();
That is sort of it, but I don't now how to put the first time in t1, what format do I put it in?
I can have PHP put it in any format, but not sure the one it needs.
Plus this appears to only put the seconds, not hours, minutes and seconds.
Is there away to do that?
Thanks,
Richard

From your question I understand you store the date and time on start?
So then you can use PHP to echo this information in a starting Date object and let a setInterval-function do the current timegetting and calculation of the time working.
See working example here: http://jsfiddle.net/c0rxkhyz/1/
This is the code:
var startDateTime = new Date(2014,0,1,23,59,59,0); // YYYY (M-1) D H m s ms (start time and date from DB)
var startStamp = startDateTime.getTime();
var newDate = new Date();
var newStamp = newDate.getTime();
var timer; // for storing the interval (to stop or pause later if needed)
function updateClock() {
newDate = new Date();
newStamp = newDate.getTime();
var diff = Math.round((newStamp-startStamp)/1000);
var d = Math.floor(diff/(24*60*60)); /* though I hope she won't be working for consecutive days :) */
diff = diff-(d*24*60*60);
var h = Math.floor(diff/(60*60));
diff = diff-(h*60*60);
var m = Math.floor(diff/(60));
diff = diff-(m*60);
var s = diff;
document.getElementById("time-elapsed").innerHTML = d+" day(s), "+h+" hour(s), "+m+" minute(s), "+s+" second(s) working";
}
timer = setInterval(updateClock, 1000);
<div id="time-elapsed"></div>
Attention! The month number in the new Date() declaration is minus one (so January is 0, Feb 1, etc)!

I would use momentJS fromNow function.
You can get the time started as variable on page load then call fromNow on that and current time to get time between the two every time the clock is clicked:
var StartedWorkDateTime = GetStartedTime();
moment(StartedWorkDateTime).fromNow(true);
Non momentJS:
var date1 = new Date("7/11/2010 15:00");
var date2 = new Date("7/11/2010 18:00");
var timeDiff = Math.abs(date2.getTime() - date1.getTime());
var diffHours = Math.ceil(timeDiff / (1000 * 3600));
alert(diffHours);
reference

Get the difference between two dates by subtracting them:
var duration = end - start;
This will give you the number of milliseconds between the dates. You can use the milliseconds to figure out hours, minutes, and seconds. Then it's just a matter of string manipulation and writing the value to the page. To update the timer once per second, use setInterval():
setInterval(writeDuration, 1000);

Create a scheduled Greasemonkey script

I need to create a special kind of script.
I want to show a message at certain times of the day. I've tested the code in Firebug Console and it works. The code is:
//Getting the hour minute and seconds of current time
var nowHours = new Date().getHours() + '';
var nowMinutes = new Date().getMinutes() + '';
var nowSeconds = new Date().getSeconds() + '';
var this_event = nowHours + nowMinutes + nowSeconds;
//172735 = 4PM 25 Minutes 30 Seconds. Just checked if now is the time
if (this_event == "162530") {
window.alert("Its Time!");
}
I feel that the Script is not running every second. For this to work effectively, the script has to be able to check the hour minutes and second "Every Second". I'm not worried about the performance, I just have to be accurate about the timing (to the second).
How do I do this?

Of course the script isn't running each second, GM-scripts run once when the document has been loaded.
Calculate the difference between the current time and the target-time and use a timeout based on the difference:
var now=new Date(),
then=new Date(),
diff;
then.setHours(16);
then.setMinutes(15);
then.setSeconds(30);
diff=then.getTime()-now.getTime();
//when time already has been reached
if(diff<=0){
window.alert('you\'re late');
}
//start a timer
else{
window.setTimeout(function(){window.alert('it\'s time');},diff);
}

Javascript doesn't guarantee your timeouts and other such events fire exactly on-time.
You should compare two Date objects using >= and remove the timeout or what ever other method you're using for tracking the time inside the matching if (and then reset it if necessary).
For more details see: https://stackoverflow.com/a/19252674/1470607
Alternatively you can use string comparison (but with caveats): https://stackoverflow.com/a/6212411/1470607