I will try my best to explain my problem in a correct english.
I have a global countdown in ajax which display the timeleft (calculated with server time) with a setinterval.
The aim is to call a function only once when the timeleft reach some target.
$timeLeft = strtotime($wallet->date_upd)- time();
if ($timeLeft <= 3)
{
function() 'this function update or not $wallet->date_upd to add time'
}
As the ajax countdown is global, and due to transfer and rendering delays, the function can be called by several users.. Any ideas?
I asume that when the timleft is over and your script runs that you also update the date_upd to a new time?
In that case you can just do the update and check if there is an affected row.
If another script was faster than the WHERE in the query will not work anymore and the affected_rows will be 0.
$new_date_upd = date('Y-m-d H:i:s', strtotime('+2 hours'));
mysql_query("UPDATE wallet SET date_upd = '{$new_date_upd}' WHERE date_upd = '{$wallet->date_upd}'");
if (mysql_affected_rows() > 0) {
// this script is the only one doing this stuff
}
So that should be something working in MySQL.
If you're managing your own server and can install some stuff then I advise you to checkout Redis.io which is a great tool for doing in memory stuff ( like an advanced memcache ) and it can also help you with doing 'locking' in a nice way
Related
I would like to have a countdown timer always show a countdown for every new user. Basically, if I close the webpage, and reopen it, the timer should still be running. I'm thinking of using the JS variable code functions to define a new client's timezone together with an if statement comment and make it a repeat loop?
Basically, I would want to run a timer on the server side, not the client side.
Has anyone done this before?
Sounds something that you could try to solve with browsers localStorage. If your only requirement is to keep saved time available after you close tab/browser and come back to your page, this is a good fit for you.
Here's a small Codesandbox example code of how to conditionally check and save to localStorage and then start counter based on that value.
https://codesandbox.io/s/4xw97q02m0
EDIT: same code pasted to a post
function setCurrentTime(){
let localStore = window.localStorage.getItem("myTime") // Check if already exists
if(localStore) return localStore
const time = Date.now(); // get current time stamp
window.localStorage.setItem("myTime", time) // Save to localStorage
return time
}
function startCount(){
const time = setCurrentTime()
const elem = document.getElementById("app")
setInterval(() => {
elem.innerHTML = `seconds since time saved:
${Math.floor((Date.now() - time) / 1000)}
`
}, 1000)
}
startCount()
<div id="app"></div>
I want to keep track of how many seconds a user spend on my project website on all of his pages and for doing this I want to use JavaScript session cookies.
This is because I will host it using Github Pages where I have no access to PHP and also because I want to try working with JS cookies (It's the first time I am doing this).
To count the seconds I am using the followings:
var time_spent = 0;
setInterval(function(){
++time_spent;
$('#counter_container span').html(time_spent);
}, 1000);
The above code works where the counter is but as expected is reseting every time I change the page.
I've tried using a js-cookie library (https://github.com/js-cookie/js-cookie) in the following manner:
Cookies.set('time_spent', time_spent);
var counted_time = Cookies.get('time_spent');
console.log(counted_time);
But the counted_time variable is always 'undefined' whatever I've tried.
I would really apreciate any guidance I can get in order to solve this little issue.
I wouldn't use a timer for this. Instead try setting a timestamp when the user enters the page, and then onbeforeunload get the duration and add it to the value stored in the cookie. Something like this:
var load = new Date();
window.onbeforeunload = function() {
var leave = new Date();
var duration = leave.getTime() - load.getTime() / 1000;
var counted_time = parseFloat(Cookies.get('time_spent')) || 0;
Cookies.set('time_spent', counted_time + duration);
}
Working example
I’m making a html & Javascript game and I’m currently trying to write some code that will show the player’s gold balance on the screen and make it decrement by 1 every time the player clicks on a Javascript object (this object is placed in a div on the html page).
I’m going to grab the balance from my database using AJAX on page load, and then place it inside a <div> but I have no idea how to make this figure decrement by 1 every time the Javascript object is clicked.
I don’t want the figure to decrement below 0. Instead, whenever it reaches 0 I want to initiate a Javascript modal to inform the player that they’ve run out of coins.
~~
Originally I was trying to use websockets to display the player’s balance on screen, but I found it very confusing (I’m a beginner at programming in general), so I’m now trying to load the balance on page load, then post the updated balance amount back to my database using AJAX every 60 seconds, or whenever the user closes the browser window, refreshes the page or navigates away from the page. I don’t know if it’s possible to do all these things, or where to start, maybe this is a really bad way to go about this and maybe it's not scalable (maybe the database wouldn't support constant updates from 1000s of players by using this method)?
I would really appreciate any advice or help anyone could give me on any of this.
Thanks in advance!
I’m going to grab the balance from my database using AJAX on page load, and then place it inside a but I have no idea how to make this figure decrement by 1 every time the Javascript object is clicked.
Here are two divs: you store the total number of coins in one and you click the second one to lose coins
<div id="coins">10</div>
<div onCLick="javascript:loseCoin()">If you click here it will cost you 1 coin</div>
Using a function to decrement the cost.
function loseCoin(){
var coins = getElementByid("coins");
var coins_nr = parseInt(coins.innerHTML,10);
if( coins_nr> 0 ){
coins.innerHTML = coins_nr - 1;
} else {
showModal();
}
}
Where showModal() will be your modal (ask if you don't know how to make it)
As for updating the database every 60 sec, you would need a timer loop such as:
setInterval(function () {
// get number of coins from your div's innerHTML
// then call your ajax controller to update DB
}, 60000);
An example of ajax using javascript:
var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function() {
if (xhr.readyState == XMLHttpRequest.DONE ) {
if(xhr.status == 200){
console.log(xhr.responseText);
} else {
console.log('something else other than 200 was returned');
}
}
}
xhr.open("POST", "url_of_your_controller_here", true);
xhr.send("coins="+ coins_nr);
(maybe the database wouldn't support constant updates from 1000s of
players by using this method)?
Any decent server should have no problem handling 1000 requests every 60 sec, but it may depend on how many other requests it has and the complexity of your requests.
If you are just trying to decrement a visible counter in the window on each click, you can do something like this:
HTML:
<div id="coinsRemaining">20</div>
code:
// use whatever click handler is appropriate to your app
document.addEventListener("click", function(e) {
var elem = document.getElementById("coinsRemaining");
// get current display text and convert to number
var cnt = +elem.textContent;
--cnt;
if (cnt >= 0) {
elem.textContent = cnt;
}
if (cnt <= 0) {
alert("There are no more coins");
}
});
Working demo: http://jsfiddle.net/jfriend00/s9jb6uhf/
It seems like you don't need to update the database on every click unless there's some realtime aspect of your coin balance that affects other users. If you're just keeping track of your coin balance for future web page visits, then you could update the database much less often than every click.
I need to do a simple pdf with some 3D objects for an oral presentation. I made several views, each one with a camera viewpoint, an object and a display mode.
To avoid the need to manually switch between the different viewpoints with the context menu, I would like the viewpoints to switch automatically with a Timer (each viewpoint staying for a few seconds). And I would like to not have to touch the mouse at all (nor the keyboard), so I would like to have the playback started as soon as the page appears.
I found the javascript command runtime.setView(N,x) to switch to the x'th view among N, but I don't know where to put it (I don't want to define a function which will be called when I press a button, since I want everything to be automated). Also, I don't know how to pause for a few seconds.
Any help ? Thanks !
I believe you're looking for setInterval(fn, time) which will call a function periodically at a time interval that you set. I'm not familiar with the setView() method you mentioned, but here's some pseudo code that you would put in tags at the end of the document body.
function startSwitcher()
var viewNum = 0;
var maxViews = 5; // you set this to how many views there are
setInterval(function() {
++viewNum;
if (viewNum >= maxViews) {
viewNum = 0;
}
runtime.setView(N, viewNum); // you will have to figure out this line
}, 2000);
}
startSwitcher();
The 2000 is 2000 milliseconds and is the time interval between executing the function. You can put any number of milliseconds there.
The runtime.setView(N, viewNum) line is something you will have to figure out as I am not familiar with whatever library you're trying to use there. The operative part of this code is the viewNum variable which configures which view in rotation should be next.
I think the runtime.SetView(..) Methods works with the name of the view as a string instead of the viewnumber. I have this function in a Dokument-level script and it works for me:
// view is the name of the view for example "TopView"
function setView(view){
console.println("Navigating to view: "+view);
var pageIndex = this.pageNum;
var annotIndex = 0;
var c3d = this.getAnnots3D( pageIndex )[ annotIndex ].context3D;
c3d.runtime.setView(view, true);
}
Combine this with the setInterval(..) from jfriend00´s answer und you should get what you need.
Best regards
I have a countdown timer which uses ajax calls to update itself. Something like
<div class="timer5">--:--:--</div>
I want to call a PHP function (only once) using jQuery which will update the database once the timer goes to 00:00:00.
The thing is, the timer can be increased at any time (it's an auction) so I can't just run a script after X time that will update the DB. I have to call the script when the timer really reaches zero.
How can this be done? Is there a some sort of an event in jQuery for that?
In my experience jquery countdown plugin is good for these things.Using this plugin you can easily do this.
var auction_id = array('1','2','3','4','5') // auction ids in array
jQuery(auction_id).each(function(key, val){
jQuery('.countbox-'+val).countdown({
//other options ref in plugin link
onExpiry: function(){
sold(val); // passing argument
//ajax call goes here to update db
}
});
}
To update your clock, I already answered here. The second part of the answer will be help full for you.
if you want to create multiple auction clock in page.you need to collect all auction ids
in array.then you can create clock for each of auction.
If it's done using AJAX you already get a call to your server, updating the timer and knowing how much time is left. Do the database update there.