Develop Reference

jQuery prevent reload if button clicked

I have a jQuery datatable that immediately loads ON READY. After that, the datatable is reloaded every 30 seconds. This feature is functioning properly.
I have added a search feature that automatically reloads the datatable with new search results. This part is also functioning properly.
The problem I am experiencing is when I am using the search feature, and the new search results are returned. After 30 seconds, the new results are cleared and the datatable reloads with all of the original records.
Here is what I am currently attempting:
$(document).ready(function()
{
var searchCriteria = "";
displayBookings(searchCriteria);
var idle = 0;
var idleInterval = setInterval(timer, 30000);
$(this).mousemove(function(e){idle = 0;});
$(this).keypress(function(e){idle = 0;});
function timer()
{
idle = idle + 1;
if(idle > 2)
{
displayBookings(searchCriteria);
console.log('table reloaded');
}
}
$('#searchPending').on('click', function()
{
var isPending = 'Y';
var searchCriteria = {
isPending: isPending
};
displayBookings(searchCriteria);
});
});
The function displayBookings() takes searchCriteria. If searchCriteria is blank, then a basic query is fired. Obviously is searchCriteria contains parameters, then the same query is fired with a WHERE clause attached. I did not disclose the code for displayBookings().
All I need to do is stop the 30 second interval if the #searchPending button is clicked.

Clear the interval so it will stop loading.
clearInterval(idleInterval)
specifically in your code:
$('#searchPending').on('click', function()
{
clearInterval(idleInterval)
var isPending = 'Y';
var searchCriteria = {
isPending: isPending
};
displayBookings(searchCriteria);
});

Rather than start and stop the timer interval, since you'll run into a bit of a race condition, you can just have the "refresh" (your "timer" function) refresh using the latest search criteria. To do this, just pass the same object into your displayBookings function. E.g.
const search = { criteria: "" };
$(...).click(() => {
search.criteria = 'change it...';
displayBookings(search.criteria);
});
setInterval(() => displayBookings(search.criteria), 30000);
This way, if a refresh happens, it will use the latest search.criteria. You can achieve the same result with minimal change in your code by simply removing the var from the second searchCriteria. Currently, without removing the var, your outer criteria is being "shadowed" by your inner.
I alluded to debouncing1 in one of my comments. I misread the code and debouncing is not what you want. Instead, you want to only "refresh" if there hasn't been any user activity within some threshold. Here's an alternative from the approach you used:
let lastInteraction = 0;
function interact() {
lastInteraction = Date.now();
}
$(this).mousemove(interact);
$(this).keypress(interact);
Then in your refresh function:
if (Date.now() - lastInteraction > threshold) { ...
Implementing both the central criteria and revised idle check:
$(document).ready(function() {
const idle = {
threshold: 1000,
lastInteraction: 0,
interact() {
idle.lastInteraction = Date.now();
},
isIdle() {
return Date.now() - idle.lastInteraction > idle.threshold;
}
};
const search = { criteria: "" };
$(this).mousemove(idle.interact);
$(this).keypress(idle.interact);
setInterval(() => {
if (idle.isIdle()) {
displayBookings(search.criteria);
}
}, 30000);
$('#searchPending').on('click', () => {
search.criteria = { isPending: 'Y' };
displayBookings(search.criteria);
});
displayBookings(search.criteria);
});
1 The Wikipedia article linked to discusses debouncing with a keyboard. It's the same concept. You'd use debouncing on your displayBookings function if you plan on having it execute live as the user is typing. This would prevent too many HTTP requests from happening in a short duration of time.

node.js setInterval vs real time

I am working on a tool that require to measure certain amount of time (for example 2 minutes) since user interaction with a tool, this time also needs to be displayed for the user.
I started simple server loop for this reason:
setInterval(function() {
measure.time();
}, 10);
i created a code for to calculate:
this.reset = 0;
this.step = 100 // 10 ms server loop, adds 1 to reset === 100 is 1 second
this.time = function() {
if(this.reset === this.step) {
console.log('SPAWN', new Date());
this.reset = 0;
}
this.reset++;
};
this is the result of my approach:
The idea is to show clock for the user and update it every second, but it skips seconds rather often, what am i doing wrong?

JavaScript multiple intervals and clearInterval

I have a small program, when you click on an "entry", the editing mode is opened, and the entry is to edit locked for others. There is every 10 seconds sends an ajax request to update the timestamp in the table.
$(".entry-edit").click(function() {
// code
loopLockingVar = setInterval(function() { loopLockingFunction(id) }, 10000);
// code
});
Then I have a cancel button to updating the timestamp in the table to 0 and to clear the interval.
$(".entry-cancel").click(function() {
// code
clearInterval(loopLockingVar);
// code
});
It all works when editing only one entry, but if two or more processed simultaneously, and then click cancel, the interval for the first entry still further...
I have this tried:
var loopLockingVar;
$(".entry-edit").click(function() {
// code
if( ! loopLockingVar) {
loopLockingVar = setInterval(function() { loopLockingFunction(id) }, 10000);
}
// code
});
However, this does not work more if you cancel and again clicks on edit...

You're assigning multiple interval IDs to the same variable which will only hold the interval ID that was assigned to it last. When you clear the interval, only the interval corresponding to that ID will be cleared.
A straightforward solution would be to maintain an array of interval IDs, and then clear all intervals represented in the array. The code could look something like this:
var intervalIds = [];
$(".entry-edit").click(function() {
intervalIds.push(setInterval(function() { loopLockingFunction(id) }, 10000));
});
$(".entry-cancel").click(function() {
for (var i=0; i < intervalIds.length; i++) {
clearInterval(intervalIds[i]);
}
});

maybe you can try like this.
var loopLockingVar;
$(".entry-edit").click(loopLockingVar,function() {
// code
loopLockingVar = setInterval(function() { loopLockingFunction(id) }, 10000);
// code
});

Gmail-like countdown timer not working

I've been trying to recreate a countdown timer similar to the one gmail uses that when you get disconnected from internet. The ajax request fails then it begin a short countdown then makes another ajax request and if it fails again then begin a longer countdown and so forth. Once a determined countdown value is reached (lets say 1 minute), the countdown is maintained at 1 minute until the internet connection is recovered or the servers comes back.
I don't want to use a plugin because this code will be embedded in a micro-controller that has limited space and also prefer not to place it as external file for practical reasons, even though jQuery library will already be external.
Everything should trigger onload, and continue automatically (i.e. no control inputs will be used).
So far I've developed code that does what I want if the ajax request succeeds or fails immediately but if there is a latency on the ajax request status (as for example having the server down) the browser won't produce an immediate result and my code fails.
I know what I stated above because I actually took the server down and was been help by firebug on Mozilla Firefox to see that the ajax result (success or failure) wasn't triggered immediately but keep waiting for several seconds.
Help please!
html code:
<div id='tempFail' ></div>
jQuery code:
$(document).ready(function()
{
//do when DOM ready - http://api.jquery.com/ready/
var timerSpeed = [1000, 5000, 10000, 20000, 30000, 60000];
// current time in ms since 1/1/1970, plus the initial reload interval
var end = (new Date).getTime() + timerSpeed[1];
var n=0;
var m=0;
setInterval(function()
{
var now = (new Date).getTime();
// Current time left to re-load in seconds, sometimes it goes to negative values, see below
var secLeft = Math.floor(( end - now ) / 1000);
// if secLeft is negative multiply by zero...equal to secLeft=0, this will produce an error of one second approximately
var timeToload = (secLeft < 0) ? secLeft * 0 : secLeft;
if (n!=0)
{
//check for failed or delayed request\n\
$('#tempFail').html('Failed or delayed response. Will auto load in: '+timeToload+ ' seconds!');
}
if( (secLeft)<=0)// if reload time is reached do
{
if (m==0)//used to prevent multiple continue reloads when ajax request status is not yet defined
{
m=1;
$.getScript('script_vars.js').done(function (data)
{
//if request succeeded
m=0;
n = 0;
end = (new Date).getTime() + timerSpeed[1];
// Time to load after the initial interval set above
$('#tempFail').html('');
//other code on success here
})
.fail(function()
{
//if request failed
m=0;
n ++;
if(n==6) n=5;
switch(n){ //timer delay for failed request\n\
case 1:
end = (new Date).getTime() + timerSpeed[1];
break;
case 2:
end = (new Date).getTime() + timerSpeed[2];
break;
case 3:
end = (new Date).getTime() + timerSpeed[3];
break;
case 4:
end = (new Date).getTime() + timerSpeed[4];
break;
case 5:
end = (new Date).getTime() + timerSpeed[5];
break;
}
});
}
}
}, 1000);
});

You asked for an example so I've written the following, you may want to wrap the contents of the function within another function so you can repeat it/don't have to worry about namespaces/etc. Didn't test so don't expect bug free!
Using window.setTimeout for every action, separated each stage into it's own function so code paths can more easily be followed.
$(document).ready(function () { // http://api.jquery.com/ready/
var $tempFail = $('#tempFail'),
delay = [1000, 5000, 10000, 20000, 30000, 60000],
delay_index = 0,
delay_ends = 0,
inform_user_ref = null,
inform_user = function inform_user() {
var now = (new Date).getTime(),
delta; // for difference, calculate later
if (delay_ends > now) { // if we're waiting for a retry
delta = Math.floor((delay_ends - now ) / 1000); // calculate time to wait
$tempFail.html('Failed or delayed response. Will auto load in: '+delta+ ' seconds!'); // let people know
window.setTimeout(inform_user, 200); // loop countdown timer
// can fast refresh this as it's just a countdown
}
},
get_success = function () {
$tempFail.html('');
// .. code on success
},
get_fail = function () {
delay_index < 5 && ++delay_index; // increment delay_index
get_initialise(); // retry
window.clearTimeout(inform_user_ref); // remove any old countdown timer
inform_user_ref = inform_user(); // and display new countdown
},
get_try = function () {
$.getScript('script_vars.js')
.done(get_success)
.fail(get_fail);
},
get_initialise = function () {
delay_ends = (new Date).getTime() + delay[delay_index];
window.setTimeout(get_try, delay[delay_index]); // retry
};
get_initialise(); // initial
});

Wow! Mr Paul S. your code was crazy good. I just made a couple of adjustments to have it perfectly working as I need it.
Added the following on ajax success:
delay_index = 0; //reset delay_index
get_initialise(); // retry
so I keep the code running every 5 seconds if everything goes ok.
2.
Added two new variables: let_cntDwn_end and ajax_rqst_status to avoid countdown number jumping (to let countdown finish before beginning the next one ) and to display a message while the ajax request haven't given any result respectively.
Here is the new code:
$(document).ready(function(){ //do when DOM ready - http://api.jquery.com/ready/
var $tempFail = $('#tempFail'),
delay = [5000, 5000, 10000, 20000, 30000, 60000],
delay_index = 0,
delay_ends = 0,
inform_user_ref = null,
let_cntDwn_end = 0,
ajax_rqst_status = 0, //ajax success or failure triggered
inform_user = function inform_user() {
var now = (new Date).getTime(),
delta; // for difference, calculated later
if (delay_ends > now) { // if we're waiting for a retry
let_cntDwn_end = 1;
delta = Math.floor((delay_ends - now ) / 1000); // calculate time to wait
if (ajax_rqst_status==0){
$tempFail.html('Failed response. Will auto load in: '+delta+ ' seconds!'); // let people know
window.setTimeout(inform_user, 900); // loop countdown timer
// can fast refresh this as it's just a countdown
}
}
else {let_cntDwn_end = 0; get_try();}
},
get_success = function () {
ajax_rqst_status =0;
$tempFail.html('');
// .. code on success
delay_index = 0; //reset delay_index
get_initialise(); // retry
},
get_fail = function () {
ajax_rqst_status =0;
delay_index < 5 && ++delay_index; // increment delay_index
get_initialise(); // retry
window.clearTimeout(inform_user_ref); // remove any old countdown timer
inform_user_ref = inform_user(); // and display new countdown
},
get_try = function () {
if (let_cntDwn_end == 0){
ajax_rqst_status=1;
$tempFail.html('Waiting for Ajax request success or failure'); // let people know
$.getScript('script_vars.js')
.done(get_success)
.fail(get_fail);
}
},
get_initialise = function () {
delay_ends = (new Date).getTime() + delay[delay_index];
window.setTimeout(get_try, delay[delay_index]); // retry
};
get_initialise(); // initial
});

There's also JS lib which handles this for you by monitoring ajax requests.
https://github.com/HubSpot/offline

Facebook server time in javascript

Im trying to show on my site changeable clock synchronized with facebook server.
The fb server time is available at:
https://api.facebook.com/method/fql.query?query=SELECT+now%28%29+FROM+link_stat+WHERE+url+%3D+%271.2%27&format=json
How to make it changeable every second without refreshing the page?

Assuming some non-written functions, it should look like that:
var requestBegin = Date.now();
getServertimeFromFacebook(function callback(fbTime) {
var requestEnd = Date.now();
var latency = (requestEnd - requestBegin) / 2;
var curDevicetime = Date.now(); // = requestEnd, of course
var difference = fbTime - latency - curDeviceTime;
function clock() {
var cur = Date.now();
var curFbTime = cur + difference;
show(curFbTime); // print, log, whatever
};
setInterval(clock, …); // you could use a self-adjusting clock
// by using a setTimeout for each tick
});
You could do
show = function(t) { console.log(new Date(t).toString()); };
getServertimeFromFacebook = function(cb) {
ajax("https://api.facebook.com/method/fql.query?query=SELECT+now%28%29+FROM+link_stat+WHERE+url+%3D+%271.2%27&format=json", function(responsetext) {
var obj = JSON.parse(responsetext);
var ts = obj[0].anon,
tms = ts * 1000;
cb(tms);
});
};

I wouldn't call the API every second.
Instead, I would get the Facebook server time only one time at the beginning. And then, I would increment my time value every second by looping using javascript :
setTimeout(function() { /* increment time */ }, 1000);
Bergi: [{"anon":1354654854}] is a unix time. Indeed, Facebook often (always?) deals with time using this representation.