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Javascript - Increase time dynamically

I have a dashboard page, where I have some time values that come back from the server. These times are in the format: HH:MM:SS (13:05:01, for example). But that value only refresh when then user reloads the page. I would like to do some javascript to keep that value going on... what's the easiest easy to do that? Thanks in advance!

Can you give me a valid reason to spam the servers with requests for time over and over again when the user machine has high probability of having perfectly valid time - is connected to internet and unless user has not messed with it it's correct.
(You might have to offset for zones, not 100% about that)
Downsides of approach to ask server over and over for current time:
You will suffer from latency
You will spam server without valid need
Ability to scale is sinking very fast both by items and users
If you need to check user time matches yours, do a 1 request at the start and then compare times with a bit of offset allowed. If times don't match set the correct time on front from back and display user device time +- whatever the difference was. If they match close enough display user's device time.
Deletes all the negatives. Adds no new negatives.
EDIT upon comment:
Oh, that makes more sense. You can query server on reload but if you expect to reaload a lot (and you need a time to be static after once being set up) you can use localStorage to store it on new browsers or cookies (work for older browsers as well).
For something that is not likely to change I would not query the server again if I don't need to. In case you need / wanna query the server again specifficaly when page loads or reloads you can add this to element on that page onload="myFunction()"
In myFunction handle to call to the back and binding to text of element displaying it.

Personally, I would go about doing it with setInterval, just set it to run the function that updates your time, and set the interval, to 1000 (milliseconds) for it to change every second. You can look Here for more info.

Make server run function once per day

I have an object on my database containing rows with different dates + emails. I need the server to automatically check once every day or week if any of the listed dates are the current date, and if so send an email to that person. (Image of the object in backand below).
I have made an email "on demand action" at the server side logic and operations in backand, which works, but i have to trigger it manually. Instead i need the server to trigger it on a specific time.
Is this possible to do, and if so how?
A solution i was thinking of, is having a function which is looping through the object, checking dates and sending the emails. And then somehow make the server run this function once per day/week or something.

Cron solution is something we plan to add in the next few weeks, but in the meanwhile, we have a good FREE solution that let you do it.
The service is https://www.easycron.com.
You just need to specify the URL of the action, which you can get from the test action panel (after executing it in test mode).
To gain access to the action, you need to implement the basic authentication which means to use the masterKeyToken( Security & Auth--> Configuration) and an adminKey (Security & Auth--> Team--> click on the key icon near one of the Admins) like that:
https://masterKeyToken:adminKey#api.backand.com/1/objects/action/ObjectName1?name=YourActionName
To read more on Basic auth click here: http://docs.backand.com/en/latest/apidocs/security/#basic-authentication

Cronjobs are the way to go.
If your hoster does not support cronjobs you have no chance to do it well.
A quick google shows me that one.com MAY not support cronjobs. But I'm not sure.
Maybe ask the support.
If they does not I would choose a different hoster which is not shitty.
(Only a shitty hoster does not support crons. I'm not saying one.com is such hoster because I don't know).
If you don't want to and they don't offer crons you could use "Poor Mens Cron". It's a crappy hack from ancient times of the Internet.
You can google that because I wouldn't recommend.

Get the users local time accurately

I am working on a project which primarily uses javascript, css, html5. I need to get the local time accurately no mater where the user is located to allow user to access a module on a particular date. Assume 1 September.
How do i get the users local time accurately?
Options:
1: Use JavaScript to get the users local time and use it.
problem: The user can manually change the date time settings of his system to change the date and access the module prematurely.
2: Use server date time to enable a module on a particular date.
problem: The server could be located anywhere eg: in U.S. and people in Australia will not be able to access the module unless the date in U.S is 1 September.
Is there any other option.
Is using client IP address a option?

well, the user's time/date info is not included in the http request header, so php will not automatically have that information. You can, as you said, use javascript to get the user's time similar to what was posted here: Determine a User's Timezone -- this is with pure javascript, if you use jquery or something similar to it, you can do it very easily.
if these are registered users however, you can allow them to set a timezone in their profile/settings, and then just use THAT setting, so even if they are traveling, they will always be set to the "home" timezone.
does that help?

First of all you should always assume user may fake any data calculated on his side. Therfore using server time is more reliable.
Using IP is an option - you can find services and databases that allow you to resolve IP to country its located in. Example: http://php.net/manual/en/book.geoip.php
Lastly - why do you want efectively differend release date for various countries? They can always use someone in other country to access module in their name.

If the user gives permission, and is using a supported browser, etc, you can get their location using navigator.geolocation.getCurrentPosition().
See developer.mozilla.org/en-US/docs/Web/API/Geolocation.getCurrentPosition for parameters and more info.
You can then use a service such as provided by geonames.org. Eg, http://api.geonames.org/timezone?lat=47.01&lng=10.2&username=demo . This returns the time at the given coords.
Update as per first comment: Of course you can never trust any data coming in from outside. But you can do things to raise levels of confidence. This wasn't meant to be a full stand-alone solution.

how to get LOCAL TIME, NOT server time?

I use these lines of code to find out the local time in Gujarat - India, regardless server time set correct or not. But i noticed that this is not working. This line produce SERVER TIME, but not LOCAL TIME. It cause problem if server time change accidentally.
What is the exact solution to to get LOCAL TIME in any country in the world?
Dim zoneId As String = "Indian Standard Time"
Dim tzi As TimeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById(zoneId)
Dim result As DateTime = TimeZoneInfo.ConvertTimeFromUtc(DateTime.UtcNow, tzi)

You may want to take a look at Noda, a .net port of Joda an open source project for working with dates. This has been ported by Stack Overflows, Jon Skeet.
A couple Link that might be helpful.
http://www.codeproject.com/Articles/78213/Noda-DateTime-Extensions-for-NET
enter link description here

What you want is the correct local time, regardless of the server defined time.
First of all, the server should be configured with the correct date/time. If you can't trust it, I think you have to rely on a service provided by a third party provider to tell you the correct time.
This other question suggests services you can connect to: Web service - current time zone for a city?
If what you want is the client's time, you have to get it through Javascript and send it to the server side.
Good luck!

Monitoring User Sessions to Prevent Editing Conflict

I'm working on something similar to a pastebin (yeah, it's that generic) but allowing for multiple user editing. The obvious problem is that of multiple users attempting to edit the same file. I'm thinking along the lines of locking down the file when one user is working on it (it's not the best solution, but I don't need anything too complex), but to prevent/warn the user I'd obviously need a system for monitoring each user's edit sessions. Working with database and ajax, I'm thinking of two solutions.
The first would be to have the edit page ping the server at a arbitrary interval, say a minute, and it would update the edit session entry in the db. Then the next time a script request to edit, it checks for the most recent ping, and if the most recent was another arbitrary time ago, say five minute, then we assume that the previous user had quited and the file can be edited again. Of course, the problem with this method is that the assumption that the previous user had quited is simply an assumption. He could be having flaky wi-fi connection and simply dropped out for ten minutes, all the time with the window still open.
Of course, to deal with this problem, we'd have to have the server respond to new request from previously closed sessions with an error, telling the client side to point out to the user that his session has ended, and then deal with it by, say, saving it as another file on the server and asking the user to manually merge it, etc. It goes without saying that this is rather horrible for the end user.
So I've came around to think of another solution. It may also be possible to get a unload event to fire when the user's session ends, but I cannot be sure whether this will work reliably.
Does anybody has any other, more elegant solution to this problem?

If you expect the number of concurrent edits to the file to be minor, you could just store a version number for the file in the db, and when the user downloads the file into their browser they also get the version number. They are only allowed to upload their changes if the version number matches. First one to upload wins. When a conflict is detected you should send back the latest file and the user's changes so that the user can manually merge in the changes. The advantage is that this works even if it's the same user making two simultaneous edits. If this feature ends up being frequently used you could add client-side merging similar to what a diff tool uses (but you might need to keep the old revisions in that case).

You're probably better off going for a "merge" solution. Using this approach you only need to check for changes when the user posts their document to the server.
The basic approach would be:
1. User A gets the document for editing, document is at version 1
2. User B gets the document for editing, document is at version 1
3. User B posts some changes, including the base version number of 1
4. Server updates document, document now at version 2
5. User B posts some changes, including the base version number of 1
6. Server responds saying document has changed since the user starts editing, and sends user the new document, and their version - user will then need to perform any merging of their changes into document version 2, and post back to the server. User is essentially now editing document version 2
7. User A posts some changes, including the version number of 2
8. Server updates the document, which is now at version 3
You can still do a "ping" every minute, to get the current version number - you already know what version they're editing, so if a new version is available you can let them know and let them download the latest version to make their changes into.
The main benefit of this approach is that users never lock files, so you don't need any arbitrary "time-outs".

I would say you are on the right track. I would probably implement a hybrid solution:
Have a single table called "active_edits" or something like that with a column for the document_id, the user, and the last_update_time. Lets say your ping time is 1 minute and your timeout is 5 minutes. So a use-case would look like this:
Bob opens a document. It checks the last_update_time. If it is over 5 minutes ago, update the table with Bob and the current time. If it is not, someone else is working on the document, so give an error message. Assuming it is not being edited, Bob works on the document for a while and the client pings an update time every minute.
I would say do include a "finish editing" button and a onunload handler. Onunload, from what I understand can be flaky, but might as well add it. Both of these would send a single send-only post to the server saying that Bob is done. Even if Bob doesn't hit "finish editing" and onunload flakes out, the worst case is that another user would have to wait 5 more minutes to edit. The advantage is that if these normally work (a fair assumption) then the system works a bit better.
In the case you described where a Bob is on a bad wireless connection or takes a break: I would say this isn't a big deal. Your ping function should make sure that the document hasn't been taken over by someone else since Bob's last ping. If it has, just give Bob a message saying "someone else has started working on the document" and give them the option to reload.
EDIT: Also, I would be looking into window.onbeforeunload, not onunload. I believe it executes earlier. I believe this is the function website (slashdot included) use to allow you to confirm that you actually want to leave the page. I think it works in the major browsers except Opera.

As with this SO question How do you manage concurrent access to forms?, I would not try to implement pessimistic locking. It is simply too difficult to get working reliably in a stateless environment. Instead, I would use optimistic locking. However, in this case I used something like a SHA hash of the file to determine if the file had changed since the user last read from the file. For each request to change the file, you would run a SHA hash of the file bytes and compare it with the version you pulled when you first read the data. If had changed, you reject the change and either force the user to do their edits again (pulling a fresh copy of the file contents) or you provide a fancier conflict resolution.