Is there a way via $.ajaxSetup to throttle requests so anything after X requests in Y seconds don't happen until time has passed so throttling can reset itself? I know I could use jquery throttle,
But I am looking for a global way to effect all $.ajax, $.get, and $.post.
For example I might setup that I will only allow 20 requests in 5 seconds. On the 21st request I would have an error handler to display a message. Every 5 seconds the counter would start over so they can make requests again.
Here is a way to rateLimit all ajaxRequests. You can define a rate limit interval in MS and how many request are allowed in a given time period.
var RATE_LIMIT_IN_MS = 100;
var NUMBER_OF_REQUESTS_ALLOWED = 2;
var NUMBER_OF_REQUESTS = 0;
setInterval(function()
{
NUMBER_OF_REQUESTS = 0;
}, RATE_LIMIT_IN_MS);
$.ajaxSetup ({
beforeSend: function canSendAjaxRequest()
{
var can_send = NUMBER_OF_REQUESTS < NUMBER_OF_REQUESTS_ALLOWED;
NUMBER_OF_REQUESTS++;
return can_send;
}
});
Couldn't you put the ajax call into a function and track how often that function is called?
var globalCount = 0;
var ajaxOperations = {
init: function(){
//init
},
loadNewsletterTemplate: function(templateDataFile){
globalCount++;
$.ajax({
url: "data/" + templateDataFile,
type: "GET",
success: function(response){
globalCount--;
formProcessing.convertToHTML_newsLetter_weeklyUpdates(response);
//console.log("response" + response);
}
});
}
}
Every time ajaxOperations is called you could iterate a global number and every time a success is performed you could do a retraction, thereby maintaining a steady flow. If (globalCount < 5) {call new ajax event}
Throttle one function, isSafe(), that returns true if it's good to go or false otherwise.
In ajaxSetup, have beforeSend() return the result of isSafe(). If it is false, the request will not be sent.
I haven't tested it, but it would be something like:
const isSafe = $.throttle(numberOfMillis, () => true);
$.ajaxSetup({
beforeSend: isSafe
});
Related
A ajax code that i am using to request a page is consuming too much memory and is making the browser slow and everything lag. It seems like there is recursion going on and i dont know of any way to prevent it. Here is what the code looks like.
$(".item").each(function() {
$this = $(this);
var dataString = {s: "<?echo $_SESSION['currentview_'.$stamp]?>", r:"<?echo $search_usernumber?>", st: "<?echo $stamp?>"};
$.ajaxSetup({cache:false});
function timeLeft() {
$.ajax({
type: "POST",
url: "get_content_home.php",
dataType: "html",
data: dataString,
success: function(result) {
$this.html(result);
//console.log("a");
window.setInterval(function() {
timeLeft();
}, 500);
}
});
}
timeLeft();
});
How can i solve this problem? Thanks in advance.
You are recursing and you shouldn't be using this form of nested setInterval. Doing this, will cause an explosion of interval instances. Instead of using setInterval, schedule additional requests using setTimeout.
setInterval will fire and continue firing every interval until you tell it to stop.
setTimeout will fire once.
Let's consider the following code which should address some of the issues you are having in this question as well as your other 2 questions.
First off, as we said before, don't use setInterval unless you actually want it to run forever. Additionally, don't nest the setInterval creations unless you actually mean to.
Instead, let's create a recursive function getTimeLeft() that will handle firing the request and scheduling the next check for time left after some duration.
This example also mocks the $.ajax() function so that you can see the function in action since we don't have an actual back end to use.
// Fake server side data to keep track of time lefts
const timeLefts = {
foo: 0,
bar: 0,
fizz: 0,
buzz: 0
};
const timeLeftsUpdateInterval = setInterval(() => {
for (const [key, val] of Object.entries(timeLefts)) {
timeLefts[key] = Math.min(val + Math.random() * 10, 100);
}
if (Object.entries(timeLefts).every(([k, v]) => v >= 100)) {
clearInterval(timeLeftsUpdateInterval);
}
}, 1000);
// Mock $.ajax function to stub sending AJAX requests
function $ajax(kwargs) {
return {
done: cb => {
setTimeout(() => {
cb(timeLefts[kwargs.data.x]);
}, 500);
}
};
}
// We will check for an update every second after the last request finishes
const timeLeftCheckInterval = 1000;
// Continuously check to see how much time is left for an element
function getTimeLeft(el) {
// Make our request data
const dataString = {
s: "<?echo $_SESSION['currentview_'.$stamp]?>",
r: "<?echo $search_usernumber?>",
st: "<?echo $stamp?>",
// My custom property to make this work
x: el.dataset.item
};
// Make our request to get the time left
const req = $ajax({ // Using our mock $.ajax
type: "POST",
url: "get_content_home.php",
dataType: "html",
data: dataString
});
// Once the request has finished
req.done(data => {
// Set the time left to the element
el.innerHTML = data;
// Have some condition so that you don't check for time left forever
// Eventually there will be no time left right? Why keep checking?
if (data.timeleft <= 0) return;
// Schedule another round of checking for time left after some duration
setTimeout(() => {
getTimeLeft(el);
}, timeLeftCheckInterval);
});
}
// Kick off getting timeleft for all .items
Array.from(document.querySelectorAll(".item"))
.forEach(el => getTimeLeft(el));
<ul>
<li class="item" data-item="foo"></li>
<li class="item" data-item="bar"></li>
<li class="item" data-item="fizz"></li>
<li class="item" data-item="buzz"></li>
</ul>
This code will address the issue that you are having in 2 Ajax non-blocking because each element will have it's own logic of going and fetching time left and updating itself.
This also addresses the issue that you are potentially facing in Timer in Ajax - Preemption because now the element won't check to see how much time is left again until after the previous check is finished.
I am trying to call an action on a controller with ajax: 10 times with a 2 second delay in my MVC5 application.
Here is the code I've written:
$(document).ready(function () {
(function loop(i) {
setTimeout(function() {
var d = new Date();
console.log(d.getTime());
callAjax();
console.log("works " + i);
if (--i) loop(i);
},
2000); // ms
})(10);
function callAjax() {
$.ajax({
url: '/Home/StartElection',
type: 'POST',
data: "test",
async: true
})
.done(function (partialViewResult) {
$("#partialTable").html(partialViewResult);
});
};
});
The console log is as expected (with a 2 second delay) but the calls to the controller happen instantly - when I set a break in Visual Studio on the controller action the next call after continuing takes 2ms
I can't see why this is happening - can any one help?
Edit: I added a console log of Date.getTime() just before the ajax call & there are 2000 ms between each
You have to change this line alone async: true -> async: false
because the AJAX calls will be made asynchronous if this property is set to true.
And so your ajax calls have no time delay.
Hope this helps.
As far as your client side code is concerned it seems to be working well as far as calls are concerned. With that said here are a few things to consider when dealing with ajax:
1) You have control over the number of times that you can call a remote service but you have no control over the time it will take for that service to respond.
2) As such it is usual good practise for most cases to not make ajax calls in a loop (this somewhat defeats the general purpose of ajax). Rather use the response to each call to then make the next call (but then of course we would need to know exactly what it is you are trying to build to suggest an exact solution).
So the closest thing to what you are looking for using ajax I think would be more of something like this:
$(document).ready(function () {
/*(function loop(i) {
setTimeout(function() {
var d = new Date();
console.log(d.getTime());
callAjax();
console.log("works " + i);
if (--i) loop(i);
},
2000); // ms
})(10);*/
var i=0;
function callAjax() {
var requestTimeMessage = "fetch #"+i+" at: "+new Date().getTime();
console.log(requestMessage);
$.ajax({
url: '/Home/StartElection',
type: 'POST',
data: "test",
async: true
})
.done(function (partialViewResult) {
var requestTimeMessage = "response #"+i+" at: "+new Date().getTime();
console.log(requestMessage);
$("#partialTable").html(partialViewResult);
i++;
if(i<10) {
/*Note this assumes a quick response for each call.
* Otherwise the response together with this delay will total a wait longer than 2 seconds.
*/
setTimeout(function() {
callAjax();
2000);
}
});
};
});
But as I said. I would need to know exactly what you are trying to achieve to give more appropriate answer to your question.
Let's suppose I have some function called makeRequest(), which makes an AJAX request to a server.
Now let's suppose I am given the amount of times this request should be made, but I can't do them asynchronously but synchronously instead.
For instance, I am given the number 5, and I shall call makeRequest(), when it's done, I shall call it again, and when it's done, I shall call it again... I should end up calling it 5 times.
I'm no expert at JavaScript but I found it easy to handle asynchronous calls by the use of callbacks.
So, my makeRequest() function takes a callback argument that is to be executed when the request has succeeded.
In my previous example, I had to make the request 5 times, so the behaviour should look like:
makeRequest(function () {
makeRequest(function () {
makeRequest(function () {
makeRequest(function () {
makeRequest(function () {
});
});
});
});
});
How can I design this to behave the same for any argument given to me, be it 6, 12 or even 1?
PS: I have tried many approaches, the most common involving creating while loops that wait until a flag is set by a finished request. All of these approaches makes the browser think the script crashed and prompt the user to stop the script.
Simple, recursively call the ajax request, while keeping track of a count variable:
function makeRequest(count, finalCallback){
someAjaxCall(data, function(){
if(count > 1){
makeRequest(count - 1, finalCallback);
} else {
finalCallback && finalCallback();
}
});
}
finalCallback is a optional callback (function) that will be executed when all the requests are completed.
You can do it this way,
var i = 5; // number of calls to you function calling ajax
recurs(i); // call it initially
function recurs(count) {
makeRequest(function() {
count--; // decrement count
if (count > 1) {
recurs(count) // call function agian
}
});
}
Here I have written multiple Ajax calls using promises. This function will run synchronously. You can get the current position of response which is executed from Ajax.
var ajaxs = {
i : 0,
callback : null,
param : null,
exec_fun : function (i) {
let data_send = this.param[i];
let url = this.url;
this.promise = new Promise(function (res,rej) {
$.ajax({
url: url,
method: 'POST',
data: data_send,
dataType: 'json',
success: function(resvalidate){
res(resvalidate);
}
});
});
this.promise.then(function (resvalidate) {
let resp = resvalidate,
param = ajaxs.param,
pos = ajaxs.i,
callback_fun = ajaxs.callback_fun;
callback_fun(resp,ajaxs.i);
ajaxs.i++;
if( ajaxs.param[ajaxs.i] != undefined){
ajaxs.exec_fun(ajaxs.i);
}
});
},
each : function (url,data,inc_callback) {
this.callback_fun = inc_callback;
this.param = data;
this.url = url;
this.exec_fun(ajaxs.i);
}
};
let url = "http://localhost/dev/test_ajax.php";
let data_param = [{data : 3},{data : 1},{data : 2}];
ajaxs.each(url,data_param, function (resp,i) {
console.log(resp,i);
});
I have a LoadingStatus Function that has two options SHOW or HIDE.
The Show triggers to display when the JQUERY POST is made, the HIDE happens after the RESPONSE comes back.
The issue I'm having is that sometimes this happens so fast that it makes for a bad experience. What I thought about doing was putting in a JavaScript PAUSE, but if the POST takes a while to respond it will take even longer because of the PAUSE.
How can I have my SHOW HIDE function work together, to make sure at minimum the SHOW was displayed to the user for at least 1/2 second?
function saveBanner (action) {
if (action == 'show') {
// Display the AJAX Status MSG
$("#ajaxstatus").css("display","block");
$("#msg").text('Saving...');
}
else if (action == 'hide') {
$("#ajaxstatus").css("display","none");
$("#msg").text('');
}
};
Thanks
In your ajax success callback, you can put the hide command in a setTimeout() for 1500 miliseconds:
success: function(results) {
setTimeout(function(){
saveBanner("hide");
}, 1500);
}
Of course that would merely add 1.5 seconds onto however long the process itself took. Another solution would be to record the time the process started, with the Date object. Then, when the callback takes place, record that time and find the difference. If it's less than a second and a half, set the timeout for the difference.
/* untested */
var start = new Date();
success: function(results) {
var stop = new Date();
var difference = stop.getTime() - start.getTime();
difference = (difference > 1500) ? difference : 1500 ;
setTimeout(function(){
saveBanner("hide");
}, difference);
}
You can perform this math either inside your callback, or within the saveBanner() function itself, within the show portion you would set the starting time, within the hide() portion you would check the difference and set the setTimeout().
You can use setTimeout/clearTimeout to only show the status when the response takes longer than a set amount of time to load.
Edit:
Some untested code:
var t_id = 0;
function on_request_start()
{
t_id = setTimeout(show_message, 1000);
}
function on_request_completed()
{
clearTimeout(t_id);
hide_message();
}
The JQuery handlers should look something like the above. The message will not be shown if you receive a reply in less than a second.
var shownTime;
function saveBanner (action) {
if (action == 'show') {
// Display the AJAX Status MSG
$("#ajaxstatus").css("display","block");
$("#msg").text('Saving...');
shownTime = new Date().getTime();
}
else if (action == 'hide') {
var hideIt = function() {
$("#ajaxstatus").css("display","none");
$("#msg").text('');
};
var timeRemaining = new Date().getTime() - shownTime - 1500;
if (timeRemaining > 0) {
setTimeout(hideIt, timeRemaining);
else {
hideIt();
}
}
};
As of jQuery 1.5, you are able to extend the $.ajax functionality by using prefilters. I wanted a similar experience where a message was shown a minimum amount of time when an ajax call is made.
By using prefilters, I can now add a property to the ajax call named "delayedSuccess" and pass it a time in milliseconds. The time that is passed in is the minimum amount of time the ajax call will wait to call the success function. For instance, if you passed in 3000 (3 seconds) and the actual ajax call took 1.3 seconds, the success function would be delayed 1.7 seconds. If the original ajax call lasted more than 3 seconds, the success function would be called immediately.
Here is how I achieved that with an ajax prefilter.
$.ajaxPrefilter(function (options, originalOptions, jqXHR) {
if (originalOptions.delaySuccess && $.isFunction(originalOptions.success)) {
var start, stop;
options.beforeSend = function () {
start = new Date().getTime();
if ($.isFunction(originalOptions.beforeSend))
originalOptions.beforeSend();
};
options.success = function (response) {
var that = this, args = arguments;
stop = new Date().getTime();
function applySuccess() {
originalOptions.success.apply(that, args);
}
var difference = originalOptions.delaySuccess - (stop - start);
if (difference > 0)
setTimeout(applySuccess, difference);
else
applySuccess();
};
}
});
I first check to see if the delaySuccess and success options are set. If they are, I then override the beforeSend callback in order set the start variable to the current time. I then override the success function to grab the time after the ajax call has finish and subtract the difference from the original delaySuccess time. Finally, a timeout is set to the computed time which then calls the original success function.
I found this to be a nice way to achieve this effect and it can easily be used multiple times throughout a site.
I'm a novice-to-intermediate JavaScript/jQuery programmer, so concrete/executable examples would be very much appreciated.
My project requires using AJAX to poll a URL that returns JSON containing either content to be added to the DOM, or a message { "status" : "pending" } that indicates that the backend is still working on generating a JSON response with the content. The idea is that the first request to the URL triggers the backend to start building a JSON response (which is then cached), and subsequent calls check to see if this JSON is ready (in which case it's provided).
In my script, I need to poll this URL at 15-second intervals up to 1:30 mins., and do the following:
If the AJAX request results in an error, terminate the script.
If the AJAX request results in success, and the JSON content contains { "status" : "pending" }, continue polling.
If the AJAX request results in success, and the JSON content contains usable content (i.e. any valid response other than { "status" : "pending" }), then display that content, stop polling and terminate the script.
I've tried a few approaches with limited success, but I get the sense that they're all messier than they need to be. Here's a skeletal function I've used with success to make a single AJAX request at a time, which does its job if I get usable content from the JSON response:
// make the AJAX request
function ajax_request() {
$.ajax({
url: JSON_URL, // JSON_URL is a global variable
dataType: 'json',
error: function(xhr_data) {
// terminate the script
},
success: function(xhr_data) {
if (xhr_data.status == 'pending') {
// continue polling
} else {
success(xhr_data);
}
},
contentType: 'application/json'
});
}
However, this function currently does nothing unless it receives a valid JSON response containing usable content.
I'm not sure what to do on the lines that are just comments. I suspect that another function should handle the polling, and call ajax_request() as needed, but I don't know the most elegant way for ajax_request() to communicate its results back to the polling function so that it can respond appropriately.
Any help is very much appreciated! Please let me know if I can provide any more information. Thanks!
You could use a simple timeout to recursively call ajax_request.
success: function(xhr_data) {
console.log(xhr_data);
if (xhr_data.status == 'pending') {
setTimeout(function() { ajax_request(); }, 15000); // wait 15 seconds than call ajax request again
} else {
success(xhr_data);
}
}
Stick a counter check around that line and you've got a max number of polls.
if (xhr_data.status == 'pending') {
if (cnt < 6) {
cnt++;
setTimeout(function() { ajax_request(); }, 15000); // wait 15 seconds than call ajax request again
}
}
You don't need to do anything in your error function unless you want to put an alert up or something. the simple fact that it error will prevent the success function from being called and possibly triggering another poll.
thank you very much for the function. It is a little bit buggy, but here is the fix. roosteronacid's answer doesn't stop after reaching the 100%, because there is wrong usage of the clearInterval function.
Here is a working function:
$(function ()
{
var statusElement = $("#status");
// this function will run each 1000 ms until stopped with clearInterval()
var i = setInterval(function ()
{
$.ajax(
{
success: function (json)
{
// progress from 1-100
statusElement.text(json.progress + "%");
// when the worker process is done (reached 100%), stop execution
if (json.progress == 100) clearInterval(i);
},
error: function ()
{
// on error, stop execution
clearInterval(i);
}
});
}, 1000);
});
The clearInterval() function is becomming the interval id as parameter and then everything is fine ;-)
Cheers
Nik
Off the top of my head:
$(function ()
{
// reference cache to speed up the process of querying for the status element
var statusElement = $("#status");
// this function will run each 1000 ms until stopped with clearInterval()
var i = setInterval(function ()
{
$.ajax(
{
success: function (json)
{
// progress from 1-100
statusElement.text(json.progress + "%");
// when the worker process is done (reached 100%), stop execution
if (json.progress == 100) i.clearInterval();
},
error: function ()
{
// on error, stop execution
i.clearInterval();
}
});
}, 1000);
});
You can use javascript setInterval function to load the contents each and every 5 sec.
var auto= $('#content'), refreshed_content;
refreshed_content = setInterval(function(){
auto.fadeOut('slow').load("result.php).fadeIn("slow");},
3000);
For your reference-
Auto refresh div content every 3 sec