DOM Elements created with jQuery AJAX call not freed from memory - javascript

I asked this yesterday but have added more information and restructured the question.
I have built a web app for a digital signage system that will be constantly running.
There is a jQuery AJAX call that retrieves html from the server and replaces the content of a div with the response so that there is no visible ugly page refresh.
The problem is that the browser is running out of memory and crashing after several hours of operation. Looking at the timeline in Chrome, it seems that although the HTML elements are replaced, they are somehow kept in the DOM.
The following jQuery code produces the following timeline:
function loadDiary()
{
if ((diaryBusy == false) && (navigatorOnline))
{
diaryBusy = true;
$.ajax (
{
url : '/get/data/from/server',
cache : false,
success : function(response)
{
$('#diary').empty();
$('#diary').html(response);
diaryBusy = false;
loadDiaryTimer();
},
error : function()
{
diaryBusy = false;
loadDiaryTimer();
}
}
);
}
}
The following javascript produces the following timeline:
function loadDiary()
{
if ((diaryBusy == false) && (navigatorOnline))
{
diaryBusy = true;
xmlhttp.onreadystatechange = function()
{
if (xmlhttp.readyState == 4 && xmlhttp.status == 200)
{
document.getElementById('diary').innerHTML = '';
document.getElementById('diary').innerHTML = xmlhttp.responseText;
diaryBusy = false;
loadDiaryTimer();
}
}
xmlhttp.open('GET','/get/data/from/server',true);
xmlhttp.send();
}
}
You can see that with the jQuery the number of nodes growing to 358278 in the short test when only 1835 are required.
This is forcing garbage collection sooner yet the memory usage increases over time.
In the second example, the maximum number of nodes is 1835 and garbage collection was never needed.
The second piece of code would be fine, but I need to attach a jQuery plugin to some of the dynamic content so a non jQuery solution isn't an option.
Any suggestions why this may be happening and how to stop the number of elements growing?
Thanks for reading.

Related

Freeing DOM element memory / resources created by ajax request

I have created a web page that displays data retrieved from a database via a jQuery $.ajax call. The web page is part of a digital signage system that will be displayed continuously.
The $.ajax response is formatted HTML generated server side. This HTML is then inserted into a div element after removing any existing HTML from the div.
I then attach a jQuery marquee plugin (http://aamirafridi.com/jquery/jquery-marquee-plugin) to some of the newly created div elements with the .marquee class.
var marqueeCounter = 0;
var appBusy = false;
function update() {
if (appBusy == false) {
$.ajax({
url: '/get/html/from/server',
cache: false,
success: function (response) {
$('#div-container').empty();
$('#div-container').html('');
$('#div-container').html(response);
$('.marquee').each(function () {
$(this).width($(this).parent().width());
});
$('.marquee').bind('beforeStarting',function () {
appBusy = true;
marqueeCounter++;
}).bind('finished', function () {
$(this).marquee('pause');
marqueeCounter--;
if (marqueeCounter < 1) {
appBusy = false;
}
}).marquee({
duration: 3500,
allowCss3Support: true,
duplicated: false
});
}
});
}
setTimeout(update, 5000);
}
The problem I am facing is that after hours of running this app, the marquees gradually slow down and eventually the browser (firefox) crashes.
Looking at the memory usage in firefox and chrome, the elements that are replaced with each $.ajax call don't seem to be freed from memory and the eventually choke the browser.
The DOM element count goes up and up as does memory usage.
I'm probably doing something fundamentally wrong here but cannot figure out how to free these resources up.
Thanks.
EDIT 1:
I have tried using the plugins destroy method as per the example on the developers page but it didn't help.
I have removed references to the plugin which results in the following code:
function update() {
if (appBusy == false) {
$.ajax({
url: '/get/html/from/server',
cache: false,
success: function (response) {
$('#div-container').empty();
$('#div-container').html(response);
}
});
}
setTimeout(update, 5000);
}
The number of nodes continues to grow and never decreases.
EDIT 2:
I have re-written this function in native javascript and the problem seems to have gone away.
function update()
{
if (window.XMLHttpRequest)
{
xmlhttp = new XMLHttpRequest();
}
else {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function()
{
if (xmlhttp.readyState == 4 && xmlhttp.status == 200)
{
document.getElementById("div-container").innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open("GET", "/get/html/from/server", true);
xmlhttp.send();
setTimeout(update, 5000);
}
Why would jQuery be returning different results?

'load' event not firing when iframe is loaded in Chrome

I am trying to display a 'mask' on my client while a file is dynamically generated server side. Seems like the recommend work around for this (since its not ajax) is to use an iframe and listen from the onload or done event to determine when the file has actually shipped to the client from the server.
here is my angular code:
var url = // url to my api
var e = angular.element("<iframe style='display:none' src=" + url + "></iframe>");
e.load(function() {
$scope.$apply(function() {
$scope.exporting = false; // this will remove the mask/spinner
});
});
angular.element('body').append(e);
This works great in Firefox but no luck in Chrome. I have also tried to use the onload function:
e.onload = function() { //unmask here }
But I did not have any luck there either.
Ideas?
Unfortunately it is not possible to use an iframe's onload event in Chrome if the content is an attachment. This answer may provide you with an idea of how you can work around it.
I hate this, but I couldn't find any other way than checking whether it is still loading or not except by checking at intervals.
var timer = setInterval(function () {
iframe = document.getElementById('iframedownload');
var iframeDoc = iframe.contentDocument || iframe.contentWindow.document;
// Check if loading is complete
if (iframeDoc.readyState == 'complete' || iframeDoc.readyState == 'interactive') {
loadingOff();
clearInterval(timer);
return;
}
}, 4000);
You can do it in another way:
In the main document:
function iframeLoaded() {
$scope.$apply(function() {
$scope.exporting = false; // this will remove the mask/spinner
});
}
var url = // url to my api
var e = angular.element("<iframe style='display:none' src=" + url + "></iframe>");
angular.element('body').append(e);
In the iframe document (this is, inside the html of the page referenced by url)
window.onload = function() {
parent.iframeLoaded();
}
This will work if the main page, and the page inside the iframe are in the same domain.
Actually, you can access the parent through:
window.parent
parent
//and, if the parent is the top-level document, and not inside another frame
top
window.top
It's safer to use window.parent since the variables parent and top could be overwritten (usually not intended).
you have to consider 2 points:
1- first of all, if your url has different domain name, it is not possible to do this except when you have access to the other domain to add the Access-Control-Allow-Origin: * header, to fix this go to this link.
2- but if it has the same domain or you have added Access-Control-Allow-Origin: * to the headers of your domain, you can do what you want like this:
var url = // url to my api
var e = angular.element("<iframe style='display:none' src=" + url + "></iframe>");
angular.element(document.body).append(e);
e[0].contentWindow.onload = function() {
$scope.$apply(function() {
$scope.exporting = false; // this will remove the mask/spinner
});
};
I have done this in all kinds of browsers.
I had problems with the iframe taking too long to load. The iframe registered as loaded while the request wasn't handled. I came up with the following solution:
JS
Function:
function iframeReloaded(iframe, callback) {
let state = iframe.contentDocument.readyState;
let checkLoad = setInterval(() => {
if (state !== iframe.contentDocument.readyState) {
if (iframe.contentDocument.readyState === 'complete') {
clearInterval(checkLoad);
callback();
}
state = iframe.contentDocument.readyState;
}
}, 200)
}
Usage:
iframeReloaded(iframe[0], function () {
console.log('Reloaded');
})
JQuery
Function:
$.fn.iframeReloaded = function (callback) {
if (!this.is('iframe')) {
throw new Error('The element is not an iFrame, please provide the correct element');
}
let iframe = this[0];
let state = iframe.contentDocument.readyState;
let checkLoad = setInterval(() => {
if (state !== iframe.contentDocument.readyState) {
if (iframe.contentDocument.readyState === 'complete') {
clearInterval(checkLoad);
callback();
}
state = iframe.contentDocument.readyState;
}
}, 200)
}
Usage:
iframe.iframeReloaded(function () {
console.log('Reloaded');
})
I've just noticed that Chrome is not always firing the load event for the main page so this could have an effect on iframes too as they are basically treated the same way.
Use Dev Tools or the Performance api to check if the load event is being fired at all.
I just checked http://ee.co.uk/ and if you open the console and enter window.performance.timing you'll find the entries for domComplete, loadEventStart and loadEventEnd are 0 - at least at this current time:)
Looks like there is a problem with Chrome here - I've checked it on 2 PCs using the latest version 31.0.1650.63.
Update: checked ee again and load event fired but not on subsequent reloads so this is intermittent and may possibly be related to loading errors on their site. But the load event should fire whatever.
This problem has occurred on 5 or 6 sites for me now in the last day since I noticed my own site monitoring occasionally failed. Only just pinpointed the cause to this. I need some beauty sleep then I'll investigate further when I'm more awake.

Not able to check popup blocker is enabled or not in chrome [duplicate]

I am aware of javascript techniques to detect whether a popup is blocked in other browsers (as described in the answer to this question). Here's the basic test:
var newWin = window.open(url);
if(!newWin || newWin.closed || typeof newWin.closed=='undefined')
{
//POPUP BLOCKED
}
But this does not work in Chrome. The "POPUP BLOCKED" section is never reached when the popup is blocked.
Of course, the test is working to an extent since Chrome doesn't actually block the popup, but opens it in a tiny minimized window at the lower right corner which lists "blocked" popups.
What I would like to do is be able to tell if the popup was blocked by Chrome's popup blocker. I try to avoid browser sniffing in favor of feature detection. Is there a way to do this without browser sniffing?
Edit: I have now tried making use of newWin.outerHeight, newWin.left, and other similar properties to accomplish this. Google Chrome returns all position and height values as 0 when the popup is blocked.
Unfortunately, it also returns the same values even if the popup is actually opened for an unknown amount of time. After some magical period (a couple of seconds in my testing), the location and size information is returned as the correct values. In other words, I'm still no closer to figuring this out. Any help would be appreciated.
Well the "magical time" you speak of is probably when the popup's DOM has been loaded. Or else it might be when everything (images, outboard CSS, etc.) has been loaded. You could test this easily by adding a very large graphic to the popup (clear your cache first!). If you were using a Javascript Framework like jQuery (or something similar), you could use the ready() event (or something similar) to wait for the DOM to load before checking the window offset. The danger in this is that Safari detection works in a conflicting way: the popup's DOM will never be ready() in Safari because it'll give you a valid handle for the window you're trying to open -- whether it actually opens or not. (in fact, i believe your popup test code above won't work for safari.)
I think the best thing you can do is wrap your test in a setTimeout() and give the popup 3-5 seconds to complete loading before running the test. It's not perfect, but it should work at least 95% of the time.
Here's the code I use for cross-browser detection, without the Chrome part.
function _hasPopupBlocker(poppedWindow) {
var result = false;
try {
if (typeof poppedWindow == 'undefined') {
// Safari with popup blocker... leaves the popup window handle undefined
result = true;
}
else if (poppedWindow && poppedWindow.closed) {
// This happens if the user opens and closes the client window...
// Confusing because the handle is still available, but it's in a "closed" state.
// We're not saying that the window is not being blocked, we're just saying
// that the window has been closed before the test could be run.
result = false;
}
else if (poppedWindow && poppedWindow.test) {
// This is the actual test. The client window should be fine.
result = false;
}
else {
// Else we'll assume the window is not OK
result = true;
}
} catch (err) {
//if (console) {
// console.warn("Could not access popup window", err);
//}
}
return result;
}
What I do is run this test from the parent and wrap it in a setTimeout(), giving the child window 3-5 seconds to load. In the child window, you need to add a test function:
function test() {}
The popup blocker detector tests to see whether the "test" function exists as a member of the child window.
ADDED JUNE 15 2015:
I think the modern way to handle this would be to use window.postMessage() to have the child notify the parent that the window has been loaded. The approach is similar (child tells parent it's loaded), but the means of communication has improved. I was able to do this cross-domain from the child:
$(window).load(function() {
this.opener.postMessage({'loaded': true}, "*");
this.close();
});
The parent listens for this message using:
$(window).on('message', function(event) {
alert(event.originalEvent.data.loaded)
});
Hope this helps.
Just one improvement to InvisibleBacon's snipet (tested in IE9, Safari 5, Chrome 9 and FF 3.6):
var myPopup = window.open("popupcheck.htm", "", "directories=no,height=150,width=150,menubar=no,resizable=no,scrollbars=no,status=no,titlebar=no,top=0,location=no");
if (!myPopup)
alert("failed for most browsers");
else {
myPopup.onload = function() {
setTimeout(function() {
if (myPopup.screenX === 0) {
alert("failed for chrome");
} else {
// close the test window if popups are allowed.
myPopup.close();
}
}, 0);
};
}
The following is a jQuery solution to popup blocker checking. It has been tested in FF (v11), Safari (v6), Chrome (v23.0.127.95) & IE (v7 & v9). Update the _displayError function to handle the error message as you see fit.
var popupBlockerChecker = {
check: function(popup_window){
var _scope = this;
if (popup_window) {
if(/chrome/.test(navigator.userAgent.toLowerCase())){
setTimeout(function () {
_scope._is_popup_blocked(_scope, popup_window);
},200);
}else{
popup_window.onload = function () {
_scope._is_popup_blocked(_scope, popup_window);
};
}
}else{
_scope._displayError();
}
},
_is_popup_blocked: function(scope, popup_window){
if ((popup_window.innerHeight > 0)==false){ scope._displayError(); }
},
_displayError: function(){
alert("Popup Blocker is enabled! Please add this site to your exception list.");
}
};
Usage:
var popup = window.open("http://www.google.ca", '_blank');
popupBlockerChecker.check(popup);
Hope this helps! :)
Rich's answer isn't going to work anymore for Chrome. Looks like Chrome actually executes any Javascript in the popup window now. I ended up checking for a screenX value of 0 to check for blocked popups. I also think I found a way to guarantee that this property is final before checking. This only works for popups on your domain, but you can add an onload handler like this:
var myPopup = window.open("site-on-my-domain", "screenX=100");
if (!myPopup)
alert("failed for most browsers");
else {
myPopup.onload = function() {
setTimeout(function() {
if (myPopup.screenX === 0)
alert("failed for chrome");
}, 0);
};
}
As many have reported, the "screenX" property sometimes reports non-zero for failed popups, even after onload. I experienced this behavior as well, but if you add the check after a zero ms timeout, the screenX property always seems to output a consistent value.
Let me know if there are ways to make this script more robust. Seems to work for my purposes though.
This worked for me:
cope.PopupTest.params = 'height=1,width=1,left=-100,top=-100,location=no,toolbar=no,menubar=no,scrollbars=no,resizable=no,directories=no,status=no';
cope.PopupTest.testWindow = window.open("popupTest.htm", "popupTest", cope.PopupTest.params);
if( !cope.PopupTest.testWindow
|| cope.PopupTest.testWindow.closed
|| (typeof cope.PopupTest.testWindow.closed=='undefined')
|| cope.PopupTest.testWindow.outerHeight == 0
|| cope.PopupTest.testWindow.outerWidth == 0
) {
// pop-ups ARE blocked
document.location.href = 'popupsBlocked.htm';
}
else {
// pop-ups are NOT blocked
cope.PopupTest.testWindow.close();
}
The outerHeight and outerWidth are for chrome because the 'about:blank' trick from above doesn't work in chrome anymore.
I'm going to just copy/paste the answer provided here: https://stackoverflow.com/a/27725432/892099 by DanielB . works on chrome 40 and it's very clean. no dirty hacks or waiting involves.
function popup(urlToOpen) {
var popup_window=window.open(urlToOpen,"myWindow","toolbar=no, location=no, directories=no, status=no, menubar=no, scrollbars=yes, resizable=yes, copyhistory=yes, width=400, height=400");
try {
popup_window.focus();
}
catch (e) {
alert("Pop-up Blocker is enabled! Please add this site to your exception list.");
}
}
How about a Promise approach ?
const openPopUp = (...args) => new Promise(s => {
const win = window.open(...args)
if (!win || win.closed) return s()
setTimeout(() => (win.innerHeight > 0 && !win.closed) ? s(win) : s(), 200)
})
And you can use it like the classic window.open
const win = await openPopUp('popuptest.htm', 'popuptest')
if (!win) {
// popup closed or blocked, handle alternative case
}
You could change the code so that it fail the promise instead of returning undefined, I just thought that if was an easier control flow than try / catch for this case.
Check the position of the window relative to the parent. Chrome makes the window appear almost off-screen.
I had a similar problem with popups not opening in Chrome. I was frustrated because I wasn't trying to do something sneaky, like an onload popup, just opening a window when the user clicked. I was DOUBLY frustrated because running my function which included the window.open() from the firebug command line worked, while actually clicking on my link didn't! Here was my solution:
Wrong way: running window.open() from an event listener (in my case, dojo.connect to the onclick event method of a DOM node).
dojo.connect(myNode, "onclick", function() {
window.open();
}
Right way: assigning a function to the onclick property of the node that called window.open().
myNode.onclick = function() {
window.open();
}
And, of course, I can still do event listeners for that same onclick event if I need to. With this change, I could open my windows even though Chrome was set to "Do not allow any site to show pop-ups". Joy.
If anyone wise in the ways of Chrome can tell the rest of us why it makes a difference, I'd love to hear it, although I suspect it's just an attempt to shut the door on malicious programmatic popups.
Here's a version that is currently working in Chrome. Just a small alteration away from Rich's solution, though I added in a wrapper that handles the timing too.
function checkPopupBlocked(poppedWindow) {
setTimeout(function(){doCheckPopupBlocked(poppedWindow);}, 5000);
}
function doCheckPopupBlocked(poppedWindow) {
var result = false;
try {
if (typeof poppedWindow == 'undefined') {
// Safari with popup blocker... leaves the popup window handle undefined
result = true;
}
else if (poppedWindow && poppedWindow.closed) {
// This happens if the user opens and closes the client window...
// Confusing because the handle is still available, but it's in a "closed" state.
// We're not saying that the window is not being blocked, we're just saying
// that the window has been closed before the test could be run.
result = false;
}
else if (poppedWindow && poppedWindow.outerWidth == 0) {
// This is usually Chrome's doing. The outerWidth (and most other size/location info)
// will be left at 0, EVEN THOUGH the contents of the popup will exist (including the
// test function we check for next). The outerWidth starts as 0, so a sufficient delay
// after attempting to pop is needed.
result = true;
}
else if (poppedWindow && poppedWindow.test) {
// This is the actual test. The client window should be fine.
result = false;
}
else {
// Else we'll assume the window is not OK
result = true;
}
} catch (err) {
//if (console) {
// console.warn("Could not access popup window", err);
//}
}
if(result)
alert("The popup was blocked. You must allow popups to use this site.");
}
To use it just do this:
var popup=window.open('location',etc...);
checkPopupBlocked(popup);
If the popup get's blocked, the alert message will display after the 5 second grace period (you can adjust that, but 5 seconds should be quite safe).
This fragment incorporates all of the above - For some reason - StackOverflow is excluding the first and last lines of code in the code block below, so I wrote a blog on it. For a full explanation and the rest of the (downloadable) code have a look at
my blog at thecodeabode.blogspot.com
var PopupWarning = {
init : function()
{
if(this.popups_are_disabled() == true)
{
this.redirect_to_instruction_page();
}
},
redirect_to_instruction_page : function()
{
document.location.href = "http://thecodeabode.blogspot.com";
},
popups_are_disabled : function()
{
var popup = window.open("http://localhost/popup_with_chrome_js.html", "popup_tester", "width=1,height=1,left=0,top=0");
if(!popup || popup.closed || typeof popup == 'undefined' || typeof popup.closed=='undefined')
{
return true;
}
window.focus();
popup.blur();
//
// Chrome popup detection requires that the popup validates itself - so we need to give
// the popup time to load, then call js on the popup itself
//
if(navigator && (navigator.userAgent.toLowerCase()).indexOf("chrome") > -1)
{
var on_load_test = function(){PopupWarning.test_chrome_popups(popup);};
var timer = setTimeout(on_load_test, 60);
return;
}
popup.close();
return false;
},
test_chrome_popups : function(popup)
{
if(popup && popup.chrome_popups_permitted && popup.chrome_popups_permitted() == true)
{
popup.close();
return true;
}
//
// If the popup js fails - popups are blocked
//
this.redirect_to_instruction_page();
}
};
PopupWarning.init();
Wow there sure are a lot of solutions here. This is mine, it uses solutions taken from the current accepted answer (which doesn't work in latest Chrome and requires wrapping it in a timeout), as well as a related solution on this thread (which is actually vanilla JS, not jQuery).
Mine uses a callback architecture which will be sent true when the popup is blocked and false otherwise.
window.isPopupBlocked = function(popup_window, cb)
{
var CHROME_CHECK_TIME = 2000; // the only way to detect this in Chrome is to wait a bit and see if the window is present
function _is_popup_blocked(popup)
{
return !popup.innerHeight;
}
if (popup_window) {
if (popup_window.closed) {
// opened OK but was closed before we checked
cb(false);
return;
}
if (/chrome/.test(navigator.userAgent.toLowerCase())) {
// wait a bit before testing the popup in chrome
setTimeout(function() {
cb(_is_popup_blocked(popup_window));
}, CHROME_CHECK_TIME);
} else {
// for other browsers, add an onload event and check after that
popup_window.onload = function() {
cb(_is_popup_blocked(popup_window));
};
}
} else {
cb(true);
}
};
Jason's answer is the only method I can think of too, but relying on position like that is a little bit dodgy!
These days, you don't really need to ask the question “was my unsolicited popup blocked?”, because the answer is invariably “yes” — all the major browsers have the popup blocker turned on by default. Best approach is only ever to window.open() in response to a direct click, which is almost always allowed.
HI
I modified the solutions described above slightly and think that it is working for Chrome at least.
My solution is made to detect if popup is blocked when the main page is opened, not when popup is opened, but i am sure there are some people that can modify it.:-)
The drawback here is that the popup-window is displayed for a couple of seconds (might be possible to shorten a bit) when there is no popup-blocker.
I put this in the section of my 'main' window
<script type="text/JavaScript" language="JavaScript">
var mine = window.open('popuptest.htm','popuptest','width=1px,height=1px,left=0,top=0,scrollbars=no');
if(!mine|| mine.closed || typeof mine.closed=='undefined')
{
popUpsBlocked = true
alert('Popup blocker detected ');
if(mine)
mine.close();
}
else
{
popUpsBlocked = false
var cookieCheckTimer = null;
cookieCheckTimer = setTimeout('testPopup();', 3500);
}
function testPopup()
{
if(mine)
{
if(mine.test())
{
popUpsBlocked = false;
}
else
{
alert('Popup blocker detected ');
popUpsBlocked = true;
}
mine.close();
}
}
</script>
The popuptest looks like this:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>Popup test</title>
<script type="text/javascript" language="Javascript">
function test() {if(window.innerHeight!=0){return true;} else return false;}
</script>
</head>
<body>
</body>
</html>
As i call the test-function on the popup-page after 3500 ms the innerheight has been set correctly by Chrome.
I use the variable popUpsBlocked to know if the popups are displayed or not in other javascripts.
i.e
function ShowConfirmationMessage()
{
if(popUpsBlocked)
{
alert('Popups are blocked, can not display confirmation popup. A mail will be sent with the confirmation.');
}
else
{
displayConfirmationPopup();
}
mailConfirmation();
}
function openPopUpWindow(format)
{
var win = window.open('popupShow.html',
'ReportViewer',
'width=920px,height=720px,left=50px,top=20px,location=no,directories=no,status=no,menubar=no,toolbar=no,resizable=1,maximize:yes,scrollbars=0');
if (win == null || typeof(win) == "undefined" || (win == null && win.outerWidth == 0) || (win != null && win.outerHeight == 0) || win.test == "undefined")
{
alert("The popup was blocked. You must allow popups to use this site.");
}
else if (win)
{
win.onload = function()
{
if (win.screenX === 0) {
alert("The popup was blocked. You must allow popups to use this site.");
win.close();
}
};
}
}
As far as I can tell (from what I've tested) Chrome returns a window object with location of 'about:blank'.
So, the following should work for all browsers:
var newWin = window.open(url);
if(!newWin || newWin.closed || typeof newWin.closed=='undefined' || newWin.location=='about:blank')
{
//POPUP BLOCKED
}

How to smooth a jQuery script that takes time to execute?

I have a jQuery script that searches in the DOM and shows the results in a list.
There is a simplified version of the script here: http://jsfiddle.net/FuJta/1/
There is usually a large number of results, so the script can take a while to execute. (In the example above, this is simulated with a function that delays the script). So if you type too fast in the searchbox, the script prevents you from typing, and it feels bad.
How could I change my script so that you can type freely, and the results show up when they are ready. I want something like the facebook search : if you type too fast, the results are just delayed, but you can still type.
Html
<p>Type in foo, bar or baz for searching. It works, but it is quite slow.</p><br/>
<input type="text" id="search"/>
<div id="container" style="display:none">
<div class="element">foo</div>
<div class="element">bar</div>
<div class="element">baz</div>
</div>
<div id="results">
</div>​
Javascript
$(function() {
function refreshResults() {
var search = $('#search').val();
var $filtered = $('#container .element').clone().filter(function() {
var info = $(this).text();
return info.toLowerCase().indexOf(search) >= 0;
});
$('#results').empty();
$filtered.each(function() {
$('#results').append($(this));
});
}
// simulating script delay
function pausecomp(millis) {
var date = new Date();
var curDate = null;
do {
curDate = new Date();
}
while (curDate - date < millis);
}
$('#search').keyup(function() {
pausecomp(700);
refreshResults();
});
});​
One solution could to refresh the results only when pressing enter. This way, the delay for searching the results feels ok. But I would prefer if I just delay the results and let the user freely type.
You should perform a search like this using asynchronous techniques. No doubt Facebook uses some sort of AJAX to request search results - which means getting the results from the server. This will help prevent the UI 'freeze' that you are currently experiencing.
Here is a very simple example of what you can try (it uses JQuery for the AJAX requests):
var searchInProgress = false;//used to work out if a search is in progress
var searchInQueue = false;//used to flag if the input data has changed
function getSearchResults(searchText){
if (searchInProgress ) {
searchInQueue = true;
return;
}
searchInProgress = true;
searchInQueue = false;
$.getJSON("URL",//URL to handle AJAX query
{ searchText: searchText},//URL parameters can go here
function (data) {
//handle your returned data here
searchInProgress = false;
if (searchInQueue){//text has changed, so search again
getSearchResults();
}
});
}
$('#search').keyup(function() {
getSearchResults($(this).val());
});
A few things to note: It is probably a good idea to handle failed AJAX requests to ensure you can reset the searchInProgress flag as needed. Also, you can add delays after the keyup as desired, but this all depends on how you want it too work.
From How to delay KeyPress function when user is typing, so it doesn't fire a request for each keystroke? :
var timeoutId = 0;
$('#search').keyup(function () {
clearTimeout(timeoutId); // doesn't matter if it's 0
timeoutId = setTimeout(refreshResults, 100);
});
It does what I want indeed.
Here's a solution that divides the search process into steps, returning flow to the browser during the process to allow the UI to respond.
$(function() {
function searchFunc($element,search) {
var info = $element.text();
return info.toLowerCase().indexOf(search) >= 0;
}
var searchProcessor = null;
function restartSearch() {
console.log('Restarting...');
// Clear previous
if (searchProcessor != null) {
clearInterval(searchProcessor);
}
$('#results').empty();
// Values for the processor
var search = $('#search').val();
var elements = $('#container .element').get();
console.log('l:',elements,elements.length);
// Start processing
searchProcessor = setInterval(function() {
if (elements.length == 0) {
// Finished searching all elements
clearInterval(searchProcessor);
searchProcessor = null;
console.log('Finished.');
} else {
console.log('Checking element...');
var $checkElement = $(elements.shift());
if (searchFunc($checkElement, search)) {
$('#results').append($checkElement.clone());
}
}
}, 10);
}
$('#search').keyup(function() {
restartSearch()
});
});
It only processes one element each time. That should probably be increased so it handles perhaps 10 or 100 each time around, but the important point is that the work is divided into chunks.
This solution should also be faster than the original because it doesn't clone() everything, only the elements that were matched.

Chrome doesn't displays the dynamic css propery change by Jquery before Ajax sync call

I have a tricky problem with Google Chrome Browser.
I have the folowing HTML node:
<div class="result-req-chat pointer float-right" onclick="chat.addUser(this/*, other vars*/)" ><img src="/images/profile_icon_4.png" alt="" /></div>
On the click event it triggers the chat object's method
this.addUser = function(trigger_node, id, is_silent, session, show_block_message){
if(trigger_node){
this.bk_trigger_node.html = trigger_node.innerHTML;
this.bk_trigger_node.cn = trigger_node.className;
trigger_node.innerHTML = '';
jQuery(trigger_node).addClass("loader");
jQuery(trigger_node).removeClass("bpurple");
jQuery(trigger_node).removeClass("bgray");
jQuery(trigger_node).removeClass("button");
}
//alert('if this is executed then it displays the previous changes of the node');
if(trigger_node.innerHTML == ''){
this.addUserToChat(id, is_silent, session, show_block_message);
}
if(trigger_node){
trigger_node.innerHTML = this.bk_trigger_node.html;
trigger_node.className =this.bk_trigger_node.cn;
}
}
addUserToChat():
this.addUserToChat = function (id, is_silent, session, show_block_message){
var response = this.chat_tabs.addTab(id, null);
if(response.error){
callUrl("/me/chat/remove-session/id/"+id);
this.chat_tabs.removeTab(id);
if(show_block_message) alert(response.message);
}else{
this.createTabsBar();
if(!is_silent){
this.switchTab(id);
this.resetContainer(is_silent);
}
if(id == this.chat_tabs.active_tab){
this.active_chat_obj.refresh(session);
}
if(this.closed){
if(this.stop_check){
return;
}
this.resetContainer();
this.switchTab(id);
}
callUrl("/me/chat/add-session/id/"+id);
}
}
chat_tabs.addTab():
// creates and adds the a tab
this.addTab = function(id,name,user_data,session){
var exists = this.getTab(id);
if(!exists){
if(session){
var user_session_id = session.id;
var user_session_data = session.data;
}else{
var session = this.createSession(id);
if(session.error){
return session;
}
var user_session_id = session.id;
var user_session_data = session.data;
}
if(name){
var user_name = name;
}else{
var user_name = this.getName(id);
}
if(user_data){
var user_data = user_data;
}else{
var user_data = this.getData(id);
}
var ob = new Object({
user_id: id,
user_name: user_name,
user_data: user_data,
user_session_id: user_session_id,
user_session_data: user_session_data,
has_new:false,
chat_screen: new ChatScreen(session, id, user_name, user_data, this.main_user_id, this.main_user_photo)
});
this.chat_users.push(ob);
return ob;
}else{
return exists;
}
}
callUrl():
function getUrl(url){
return jQuery.ajax({ type: 'GET', url: url, async: false }).responseText;
}
The point is that the method addUserToChat() contains a syncronous Ajax call.
The problem with Chrome is that the trigger_node changes aren't displayed. If you watch with the built-in JS debuger then everithing goes ok ( even with displaying ) .Also if you uncomment the alert.
It runs on Mozilla ( latest version ).Also the Crome is the latest version.
I can observe that in the time that it waits for the ajax response, the page is unresponsive to events like hovers, tips etc.
Do you have any suggestions for this? How can I implement a workarround method?
Synchronous Ajax calls are bad practice! They stop the browser for the entire duration and fool the user into thinking something crashed. You really should change this.
To your question why you don't see the latest DOM changes:
When you change something in JavaScript the browser will not immediately change the DOM, because painting a ui element is far more expensive than painting a dozen. So modern browsers will try to change the DOM as lazy as possible.
There are, apart from performance other upsides, like
$('p').hide();
can hide all p elements at the same time although jQuery will select each and than change the css.
I cant't give you any hind of a workaround without understanding your code better, sorry. Thanks!
UPDATE:
After reading your code, I would think about adding some closures to the application. A basic concept of javascript is that functions are first class types. I personally think, that your program flow is less than ideal, and this is the area of improvement. the calls to call url should look something like this:
var callUrl = function(url, callback, interactionStoped) {
if(typeof interactionStoped != 'undefined' && interactionStoped == true) {
//add code to display some loading animation
}
jQuery.ajax({ type: 'GET', url: url, success: function(data) {
callback(data);
//remove loading animation here
} });
}
as a start. Then you refactor your getUrl calls.
Funny thing is in your code example you never use the response, so I don't know what your app is waiting for. Assuming it is something important you must handle the response always in your callback.
Try looking at your app as if it were a tree. A Parent Function or Object will call itself some child functions that handle different tasks, wich themselves will invoke other functions. Build methods that are small and do only one thing on a really small set of data / parameters.
I can't rewrite your complete code, but I hope this helps anyway.
When do you try to display/fill the trigger_node variable?
It seems a bit like you aren't executing this action in the callback-function of the AJAX-request. Note that if the request is still running while you try to check for trigger_node, it won't of course show your changes.

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