Develop Reference

JS/Jquery: Initiate window resize without actually resizing

So I have a very specific problem that presented itself recently (right before our planned launch day tomorrow) and I am not completely sure how to solve it. I have built our website of an HTML-template with my modest front-end skills and we are very pleased with it. However, I can't seem to solve this.
The problem:
I have a filter system that allows a user to filter articles that are presented on a page. A user can even fill in this filter on the home page, direct to the page with the articles and have the filter applied. However, if then the filter is broadened (less strict) and new articles present itself, the pictures do not show up. Found out this is the case because the flexslider behind it has to be initialized again which happens on a window load (e.g. when the window is resized). The function that controls the initialization of the flexslider is in an external js file and I am not sure whether I can call on it from my own custom.js file, so I am thinking of just calling a resize/reload window function to active it.
The question:
Can I run a resize window function (or something that activates the flexslider) without hindering user experience (more specifically, without ACTUALLY resizing/reloading the window)? I will run this on a change in the filter.
I know this is a very specific question but hopefully somebody can help me out.
Take care!
p.s. it would be ideal if I could run the actual function that loads the flexslider but this is located in an external js file.
EDIT:
Briefly some additional info. If I go straight to the article page, it has no filter active and thus shows all articles, if I then start flipping through the filter, all is good. It is however only if I arrive from the homepage with a set filter that the problems arise. You then arrive on the article page which shows only the articles that are within the boundaries, and when the filter is taken away it has problems loading the images of the new articles showing up. As if it had not loaded these because they were not open on window load the first time.

You can trigger a resize event by creating a new event and passing it into the dispatchEvent command on window. There's a nice guide here. You'll want the type of event to be resize, since that's what it's listening for.
window.dispatchEvent(new Event('resize'))
This will work for events that were added via jQuery as well as events added via addEventListener.

I managed to solve it after all by delaying the function that drops the filter values into my inputs so it loads in all images initially before applying the filter. It happens at such speed it's hardly noticeable.
Also, I did try to initiate a window resize function, it did work without actually resizing anything, but unfortunately the images did not load in properly (overlap and such).
Anyway, it has been solved. Thanks for all the input!

How to run a script every time a new page is loaded on YouTube?

Since some time last year, YouTube made it so that every page is not actually loading an entirely new page, but primarily just re-loading the contents in div#content. You can notice this when you click on a link in YouTube and see the red loading bar at the top of the page.
I have a Greasemonkey script that modified elements on YouTube, but now that YouTube doesn't reload the entire page, the Greasemonkey script no longer fires on every "new" page. How can I make the Greasemonkey script fire on every "new" page that I load on YouTube?
I'm using jQuery in this Greasemonkey script. I tried using functions like .on() with DOMNodeInserted but I can't find the right combination to make it work properly. With the event listeners that I've been using, I end up running my script hundreds of times for each page load, such as with the following:
$('div#page').on('DOMNodeInserted', 'div#content', function() { });
Another solution I was thinking of was making all links on YouTube load pages like normal, without the new way that they are doing it.

I figured it out myself after some research. First off, I don't like solutions that use setTimeout. This is often one method suggested in favor over the deprecated DOMNodeInserted for instance (which I use in some of my scripts, but try to avoid as much as possible), but if possible, I always prefer a solution where the script actually executes after a specific event. I've posted the solution I initially used in the first section below, then the final solution I used in the second section. All code below requires jQuery.
Decent solution, but not the best
At first, I had a solution where I added a click event to all A elements, which would run a timer that ran my script after 2 seconds. This isn't elegant, because if the page loads quickly, then there's a split second where the script hasn't run. And if the page loads for more than two seconds, then the script doesn't run at all. Script below:
$('a').click(function()
{
setTimeout(youtubeFunction, 2000);
});
Much better solution
So I began looking for a solution that was related to what I wanted to accomplish. I eventually found other people with a similar problem to mine (such as people wanting to create a Chrome script that modifies YouTube pages). This led me to this particular Stack Overflow solution, which basically says that the red loading bar at the top of YouTube pages was a CSS transition element, and that it created a transitionend (case sensitive) event when it was finished. The code in the linked solution wasn't complete (for me anyway), but it did explain how to achieve a working solution. The code I have runs only once per page, which is perfect. So here's what I have now:
function youtubePageChange()
{
youtubeFunction();
$('body').on('transitionend', function(event)
{
if (event.target.id != 'progress') return false;
youtubeFunction();
});
}
$(youtubePageChange);
To explain the code above, basically I run the code once for when you first load a YouTube page (such as by typing the URL in the address bar). Then for every subsequent click that requires the progress bar, the code runs again.
Red progress bar code
Oh, and for future reference, when the red progress bar appears at the top of YouTube pages, the site temporarily adds a new DIV to the end of BODY, with the following code:
<div id="progress" class="waiting" style="transition-duration: 400ms; width: 99%;"><dt></dt><dd></dd></div>

You can set a listener which gets called when the page has finished loading.
This is for the new YouTube material design:
body.addEventListener("yt-navigate-finish", function() {
//your code
});
And this for the old:
window.addEventListener("spfdone", function() {
//your code
});
(if you are using *monkey, you'll need to use unsafeWindow)
Keep in mind that the old design will be discontinued, so your script may not work after that.

Hooking into the popstate might be an option, but i was unable to make that work correctly for some reason (youtube may be preventing it from propagating), so i came up with this that shows the concept:
var currentState = "";
setInterval(function(){
if (currentState != history.state["spf-referer"]) {
currentState = history.state["spf-referer"];
console.log("Do Stuff!");
}
},250)
Just watches for the history.state to change, at which point it will log. The state should change any time the url changes, even if it wasn't due to a page reload.

CKEditor smooth setData

I am currently using CKEditor to be able to edit and to view documents in my SQL database. If I change the content of the document in the sql database it should automatically update the CKEditor instance with the new text. My only problem is that it flashes when ever it updates (ie: it goes blank and then updates to the new text). Does anyone know of a way to make it a smother transition. I'm also using JQuery so I'm not sure if there is anything that could be used there to make a smooth transition to the new text.
CKEDITOR.instances.content.setData("data");
CKEDITOR.instance.content.setData("new data");
The change from data to new data will have a quick bit of lag.

There's no way to avoid some slight flickering when setting data in framed (based on wysiwygarea plugin) editor instance. This is because the entire contents of the iframe containing your work must be re-created. This is nothing like a piece of cake and I hardly think we can bypass this thing.
I'd recommend you to play with element.setHtml( html ) on editable though:
CKEDITOR.instances.editor1.editable().setHtml( '<p>FooBar</p>' );
This is not a valid method for setting editor contents in any way because it bypasses internal filtering, processing and stuff. Yet it may work formay you if you're careful.
P.S. You'll probably also want to cache editor1.editable() object to speed-up things.
There are quite some core developers of CKEditor active on stack
overflow.
Yep. We are ;)

It seems that the screen flickers because the page is reloading an iframe within the editor. By using the divarea plugin for CKEditor I can get rid of the flickering. The only problem now is that the CKEditor.readOnly property no longer works...

Will infinite scroll cause browser crashes?

I implemented infinite scroll like so:
new_page_value = 1;
$(window).scroll(function() {
if($(window).scrollTop() >= $(document).height() - $(window).height() - 200) {
new_page_value = parseInt(new_page_value) + 1;
get_page(new_page_value);
}
});
When the user almost reaches the bottom of the page (200px left) the function get_page() is called. This contains an ajax call that gets all the contents of the new page and appends it to the <body> of the document.
Now I just realized if my site gets big and instead of having 10 small pages I have a gazillion giant pages then the user's browser might crash if they are persistent enough to keep infinite scrolling for long time.
Would this be a possible solution to this problem:
I will keep appending the new pages to the document <body> until the 10th page, after that I will be replacing the <body> content entirely instead of appending. So using html() rather than append().
I just don't know if this will actually work to prevent crashes. Will .html() clear the "memory" of prior html that was brought in via ajax?

I really think this is a common issue for many sites with AJAX list content. So let's take an example at some of the most popular ( think of scale = experience ) websites and their solutions :
Google Images
If you check out images.google.com and you search for whatever, for e.g. "guiness", you will see a page full of results (actually the images are ajax loaded, not the html-code, so the page is with fixed height) and when you scroll at the bottom there is a button "Show more results". This might be solution one of your problem, but is it really necessary to place a button at the bottom after, for e.g. the 10-th page? I really think it is generally a good solution for page usability and memory leaks, but it is really not a necessary option as we can see in :
Facebook
Facebook Newsfeed is another story. There is a button "Show more posts", but I really don't know when exactly it is displayed rather than loading the next page of posts. It happened to me once to load 10-15 pages of posts, only by scrolling. And you know Facebook posts include videos, photos, AJAX comments and a lot of more Javascript fancy stuff, which take a lot of memory. I think they've managed to do this after a lot of research, how much of the users scroll to the bottom.
Youtube
Youtube has "Load more videos" at every page, so the solution is basically similar to Google, except that Google renders the whole html of the page and on scrolling just loads the images.
Twitter
Twitter supports infinite scrolling. Yep, they do it may be because tweet is 140 characters and they don't need to worry about memory so much. After all who is willing to read more than 1000 pages of tweets at one page load. So they don't have a button for "load more" and they don't need one.
So there are two solutions :
Use infinite scrolling ( you should consider how much content you load and how rich it is )
Use button : "Load More"
Most of all, you should not delete already loaded content of a list.
Nowadays everything is Javascript and Javascript has garbage collection, so it is very hard to unload the DOM ( if it has Javascript, not plain text ) and manage to remove the Garbage from Javascript. Which means that you won't free the whole allocated memory of the unloaded content from the browser.
Also think about of your requests, why would you need to load again something, that you have already loaded at first place. It costs another server request, meaning another database request and so on.

I have worked with this before and here are some of my thoughts:
a) If you are appending data to the memory page(s) at a time then it is not an issue, some browsers might not respond well but most of the lastest browsers will render without any problem so long as there is enough memory on the target machine, you could probably see how the ram usage increases as you append pages. Use chrome for this as each page is a separate process and it has an inbuilt task manager
b) regarding usage of html(), it indeed removes the markup but it does so at a heavy cost as it tries to take care of special conditions and has an overhead and accesses all the controls nested within the container that you are replacing (not sure about the last pat), but it has a cost. A simpler way to clear the DOM would be to use the innerHTML property and set it to empty, jquery does this but it is at a later point in the html() api. open up the api and look at the method.
using innerHTML
$("<selector>")[0].innerHTML=""
Also deletion of pages sounds weird to me as a user, what if I want to go back to the initial comments and please dont think about making it an infinite scroller too.. I have tried and given up after the number of bugs raised but we had a genuine use case for it and I had to stick a button up there, but this wasnt when the user scrolled away from the first page, this is when the user landed on a 3rd page but now needs to see the results above it.
Hope that answers your question and btw infinte scrolling is your friend use it, dont over engineer a case which will probably only be tested by your QA team. Its better to spend your effort somewhere else.

Yes it will, if i may suggest an idea after let's say 5 pages just delete the first page and append the new one instead of deleted all of the previous pages. good luck :)

Manipulate DOM before it is shown to the user?

I'm not too familiar with javascript, is there a way to manipulate the DOM before the page is displayed to the user?
I'm using GWT which makes you create the page elements via javascript. This is kind of convenient, but it appears that all the javascript code is executed after the page is first shown to the user. This has the effect of showing the page as a blank white screen, then all the UI elements popping onto screen. The effect is really apparent when switching between pages.
If I were using php or jsp, it looks like the page ui elements are already prerendered and the browser won't show a blank white screen before display.
So is there any hook in javascript where we can manipulate the DOM before the browser clears out the contents of the last page shown?
-------------------------------- Edit ----------------------------------------
#Cipi: I'm not sure if this will work, but I can try. I think it will be the same problem though? I still see it happening like this:
User is already on one of my pages.
User clicks a link.
Browser starts fetching contents of new url, but the contents are simply an empty html file with just a javascript link in it.
After page is done downloading, browser renders the html (this is just a white screen).
Now the javascript starts executing in response to the onLoad() event(?), building the UI.
A few ms later, the DOM is done being manipulated, and is finally presented to the user.
so I am thinking that your solution would take place on #5, but by then the browser has already rendered the contents of the initial page on step #4?
#Crozin: I'm looking into DOMContentLoaded now, seems specific to gecko based browsers but there are solutions for ie etc. Yeah I basically want to manipulate the dom before the browser renders anything for the new page to screen, hopefully that can do it.
Thanks

Yes there are two methods:
Use DOMContentLoaded event
In the following code:
....
<p id="abc">abc</p>
<script type="text/javascript"> CODE HERE </script>
<p id="def">def</p>
Element with id abc is avaiable, but the one with id def ain't.