Pattern for pagination is currently on a after 1.0 roadmap for Meteor. Are there any examples or suggestions how to do it now? So how to nicely do an infinite scroll by subscribing to new and new elements as user is scrolling to the bottom?
I recommend that you try my package, Pages: https://github.com/alethes/meteor-pages
It's extremely easy to use (you can set it up with just one line of JavaScript), yet very customizable. It features: incremental subscriptions, local cache, neighbor prefetching, request throttling, easy integration, multiple paginations per page, bootstrap 2/3 styling, failure resistance, built-in iron-router support and a lot of settings that can be modified on the fly, without reloading the page.
There is a package on atmosphere.meteor.com for pagination that should get you started
https://github.com/egtann/meteor-pagination (Pagination)
https://github.com/tmeasday/meteor-paginated-subscription (Pagination with publish)
The second one actually sends down one page of data at a go instead of all the data at once so if you have loads of data it might help with that. With the infinite scroll you would have to attach a manual scroll listener and put in the new data by increasing the size of a page as you scroll down (not specifically moving to page 2).
I'm a bit unsure on what pattern to use specifically because using page size might be a bit troublesome unless you're able to get it to work right with reactivity which should be possible if you're able to seperate your {{#each}} block helpers so that its for each scroll down, perhaps using Meteor.render so that the entire set of data already available isn't re-rendered.
It might also work if you put the data in div block containing a scroll overflow instead of the above so that it does re-render but their position in the scroll remains the same, in effect making the re-render unnoticable.
Related
I have a single page using CSS columns that reflows on load.
Even when I remove all IMGs and iFrames, so it is fetching no
external resources, it reflows.
I can't figure out what is causing the reflow/repaint. Any CSS exports
out there able to figure this one out?
https://github.com/treenotation/dumbdown/issues/8
There's too much content in document.
The browser will gradually display the content, that is, the content involved in rendering will gradually increase, which affects the layout calculation.
You can add the "loading state" style. When window.onload Event trigger, change the style to "load complete".
Or 'Masonry Layout'.
Reason for the reflow is: a huge amount of content but NO strategy to handle with. Indeed there are many things you can avoid/do/change ...
REASON WHY - just to base the answer ...
The reflow is caused by the mechanic: at first the text (html code) has been downloaded and rendered. But there are still a lot of elements (most over images but youtube videos and iframes as well) which are still on download. As the browser don't know the size of that elements he does not keep the place for that elements.
Now: after the download and rendering of every element has finished the browser injects the element to the content and all off the following content is pushed down and in your case to next column ... reflow.
STRATEGY: MULTIPLE ACTIONS
To your question: there is not only one reason which causes multiple and long downloads. So far there is no simple single answer and even NOT A SINGLE SOLUTION. Your needed strategy will be to optimize the page by a multiple bundle of actions. But I believe doing that you can reduce it to an acceptable amount ... and maybe there is a chance.
THINGS YOU CAN DO
1. Change layout
If you change the layout to an actual web technique. That means don't use columns (flowing left to right) to a style which prepares the pageflow from up to down. Than you can asynchron load the needed elements when the user scrolls down. The technique is named Infinite scrolling: How to do an infinite scroll in plain Javascript
But I assume as the special layout has charm this won't be an option for you!?
2. Images which are not shown - remove not needed elements from download
On your page I found images which are downloaded but which are not shown on the page. (Example: 3.png with INCREDIBILE USELESS 659KB). Remove such elements from your content.
3. Reduce not needed size of elements
Additional a lot of shown images on your page have an incredibly large file size which is not needed.
Example: devices.png
image-size: 692x285px - real size
layout-size: 287x118px - needed size
file-size-download: 110kb
file-size-needed: 4kb - if (lossless) optimized
And think about: many little file downloads add up to a big amount ... and you have a lot of downloads! If you calculate: 10 images your way: 1.1 MB can be done with 40KBs
Additional:
if you you need higher solutions use srcset attributes ...
sometimes that is a practical problem with the knowledge of the editors: than teach them how to lossless reduce images and advise them the sizes to use for the images in the layout
4. Use faster server for images
It seems the download rate from your server is not the fastest one. That's normal by most providers. As you have a lot of images ... think about to load images from a faster server - if possible. Example: the pure download service from AWS (Amazon Web Service) is incredibly fast. As you just need a bucket for downloading that is not as expensive ... try it out.
5. Use placeholders for elements
As you have a lot of elements I think you maybe cannot avoid the later injection which causes the reflow. But you can use placeholders for your element so the needed place is reserved and the reflow still does not happen for this element.
Just define the html structure and possible sizes in your layout. That additional helps the editors as they know what image size they can use. Then size the placeholders with CSS and initiate an ajax image download by JS.
In case of later download now the users maybe see a placeholder at the beginning but no reflow. You can do that with few lines of code. I attach an example at the end of the posting.
NOTE: You can do this with (youtube-)videos or iframes in a similar way ;-)
6. Use vanilla instead of jQuery
As I saw has the download of jQuery an incredible impact to your download time. Really. (That's the reason why I assume your server is a slower one.) Have a look to the download time of your elements. It is one of the elements which needs the most times and blocks your elements from rendering.
jQuery is an old dog. Modern web techniques use vanilla JS ... and as I see there are no complicated things on your page you cannot realize in vanilla. So the recommendation is to remove it from you page (if possible) and you will earn a huge speed advantage.
7. Use CDNs for download when possible
Downloading frameworks and fonts from own server makes pages slow and blocks time for the page download of other elements. Use a CDN instead.
As I have seen your fonts are loaded from a CDN? But jQuery still comes from your server. If you don't want to change to vanilla chose to load it from CDN.
8. Check if Youtube can be loaded more simple
Youtube is loaded by several actions to your page. In this case I AM NOT SURE as I still did not work with youtube for a longer time. But I believe (not sure if I am right) that there is a more direct way to include youtube videos to a page. Maybe you would like to check it.
But nevertheless: work with placeholders for the video players as well. That are almost just few additional lines off css.
9. Optimizing user experience: thinking about a preloader
Reflow is not new phenomenon to webpages. Up to now a lot of pages uses preloaders to generate a better user experience. Today's technique is ajax load...
I don't know if the described techniques will avoid the reflow completely. As there are many elements the download time cannot be set to zero. But optimizing the page will reduce it dramatically. If there still remains a little bit ... maybe you like to think about the older technique. Using a nice and maybe well designed preloader symbol indeed can upgrade the user experience. Maybe on mobile views with medium data speed there is no other chance...?
But that is just to think about an additional possibility ...
[update]
10. Combine placeholder with infinite scroll
If you are using placeholders you can/should combine it with technique infinite scroll.
Means: all media (particularly images but maybe videos and iframes as well) are prepositioned by sized placeholders. That works immediately so there should be no more reflow as needed. Then load media assynchron by AJAX based on their position on their screen. Images which are in view are loaded immediately.
As you don't have so many media elements on starting viewport (most are still below the screen view) that should work as if it is a page with a 'normal number' of pictures/medias.
All others are loading afterwards when scrolling the page the media comes in view like on a 'infinite scroll page'. (Note: that works if the file size off the images is not to large, - so optimizing the images has still to be done.)
That has the additional advantage that thake makes sure that the images are loaded in the sequence they are needed ... which safes a lot of time.
Could be done in javascript:
Place images/media by placeholder technique
On window.onload check which images/media are in the viewport. Don't forget images which are only partly seen.
On window.onscroll check if image(s) comes to viewport and load image
Note: I am not quite sure if there are anchor links on your page to the single articles. I believe not. But if you still use them the starting viewport can be anywhere on the page when the user call an article. In that case window.onscroll has not only to work scrolling down but scrolling up to.
I am not quite sure if there is a ready script avaiable. But I would wonder if not. Otherwise it would not be to tricky to do that on your own. That would have the charm that such scripts mostly have less and cleaner code than preworked scripts ...
[end update]
... ... ...
I am not quite sure if the described issues are complete. Mostly there are found more possibilities to optimize a page when you start with the process. But as I had a nearer look to your page that are the most important chances.
EXAMPLE LAZY IMAGE LOAD WITH PLACEHOLDER EFFECT
Just EASY AND SIMPLIFIED example for lazy image load. Please adapt to your need.
// new html for image
<img class="placeholder-size" src="path/placeholder.jpg" data-lazy-url="https://url-to-your/imag.png" alt="Image Description">
// css
.placeholder-size {
width: 200px;
height: 100px;
}
// js for lazy load
// older code but works, please actualize if needed
window.onload = function(){
var lazyImages = document.querySelectorAll('[data-lazy-url]');
for (var i in lazyImages) if (lazyImages.hasOwnProperty(i)) {
var imgUrl = lazyImages[i].getAttribute('data-lazy-url');
lazyImages[i].src=imgUrl;
};
};
I want to know what disabling CSSOM View Scroll Coordinates flag in chrome://flags does and how can i replicate this behavior using code in my ReactJS app.
Additional information :
It seems after Chrome 85 update, ag-grid RTL support breaks and the grid is not able to scroll the content and sometimes the cells becomes white, i had to dig very deep into the past questions and try a lot of far fetched solutions to find what i have.
I found out that disabling CSSOM View Scroll Coordinates in chrome://flags will fix the bug!~ but the problem is i don't want to force my users and teach them to do this just so my app works, so i thought what ever disabling CSSOM View Scroll Coordinates does, maybe i can replicate it using css code or some other code
I have already reported this issue in ag-grid's git-hub but i'm still waiting for them to offer a solution in the mean time if i can get this to work only using code, it would be great as i have a lot of users which are not able to use my app just because of this simple bug ..
Thank you.
I would like to confirm what effect this CSS code has on the homepage of a wordpress website.
.lazy { display: none !important; }
Many thanks for explanations.
I have noticed images in the homepage are being blocked from being displayed which is why im asking this question.
The CSS code itself, prevent any element which has it from being displayed on the screen.
Due to its name, it may be used to enable something called lazyload (you can read about it here).
lazyload is usually used for several reasons:
Remove the pressure of loading many images at first; sometimes images are placed at the end of the page so the client won't see it at the top of the page, with lazy loading trick it. You can prevent those images from being loaded, and force them to load only the moment your client reach them by scrolling or other events so it cause page loading improvements (because the page is now lighter)
For making some visual effects; almost everywhere you need the image to be hidden and after some juggling or some specific events it is shown (like wp-admin and sub-menus, which will be shown if you hold your mouse on or click them)
etc
Recording to the reasons; I guess your kind of codes (which will be handled in client-side and client browser) does not fit the first reason and may be used for the second one because for the first reason it is better (and I guess it must) implemented on server-side. Why? Because in your code, the image is loaded and be will there and just not shown because of the CSS code
This was all I know but if you want a more specific answer you have to say where you saw it in WordPress, in a plugin, wp-admin, template, etc...
Hope the answer becomes handy for you
I developed a CSS-based layout for a web application that has been locked down and awaiting back-end integration. The primary element on the page is a timer/clock.
As originally intended, the timer is just a timer and is very simple. It looks like this:
Now, the boss has asked me to make a pretty significant change to my design. They want 3 tabs to hang off the bottom of the clock. They did not want this before, so I didn't build any show/hide logic and I didn't build tabs under the clock either. I am also slightly concerned because the tabs are at the bottom of the clock - that seems like a point of curiosity but I am guessing it is not huge problem either. Clicking on any of the tabs needs to cause the tab that was just clicked on to have focus, and it would cover the black rounded rectangle and display information about the tab the user clicked on. It would cover the clock. I would describe their request as reasonable, but I wish I'd had this requirement when I was coding. I think it sounds like a relative of a show/hide toggle. This is how they want the tabs to look, and where they want the tabs to go:
The part I am getting stuck on is how to slipstream something like this into what I've already created for the clock. Effectively they need me to make that component much more interactive, as the tabs have quite a bit of functionality within them. There are 3 tabs that I envision needing, but the mockup only shows 2, and that's ok.
I've included a few images in this post and I hope it helps. I've spent nearly a week smashing my head against this and I am stuck. To sum it up, I need to introduce (or shoehorn) a show/hide component as part of a late-hour change.
I am decent with CSS/JS/Web dev, but this is my Achilles heel. By "this" I mean taking a part of the UI that I already created and making it behave totally differently. In this case a pretty simple timer needs to change and has to have tabs at the bottom of the clock that would cover the clock itself when clicked. I hope I was clear enough in this question.
You have a very simple way to resolve this, using JQuery (you can use Javascript on it's own, but this will make it easier for you, less writing).
The give an ID to the DIV where you have the HTML for the clock, move the entire HTML content into a declaration like this:
$("#myDivId").html("put all the HTML content here, don't worry with the size of it");
you just need to change the HTML based on what you want to display. For easier implementation you can create a variable for each different content options, like this:
var myFirstHtmlBlock = "<p>blah blah blah</p>";
var mySecondHtmlBlock = "<span>Anything else...</span>";
and then change the content using those variables:
$("#myDivId").html(mySecondHtmlBlock);
Just let me know if this sorted out your issue.
I am going to write an application that uses QT4 (with C++ or python it isnt important in that moment).
One of functionality is "Showing all items in database".
One item has a Title, author, description and photo (constant size)
And there could be very many items. Let's say 400. There won't be enough space to show'em all at once time.
One row will have 200px, so i need at most 4 for once time.
How to paginate them? I have no idea.
I can use limit and offset in SQL queries, but how to tell window: "that's 5th page"?
Any solutions?
First off, you normally do not want to use any manually set pixel widths in any GUI application, if you do, your toolkit sucks (or you must work in game development).
Second off: be more specific.
You'll need to define "page" for your application, namely what a page should be in its context. I assume it is breaking a list of items into separate pages. Normally this is done by using one of the view classes (e.g. QListView or QTableView) to take care of much of the legwork: it's called a scrollbar (not to mention the collapsing folders concept from file managers). Another method is splitting the information across several tab pages (QTabWidget), where each page displays a view of some sort (Perhaps QTextView or one of the M/V or Item view classes).
Same thing can also be done using your own widget stack and some other widget to manipulate the currently displayed page. This is basically how the option dialogs in the TeamSpeak 3 client and most KDE apps work; it's also how wizards with back/next buttons work in concept. I suggest you take a look at this config dialog example
Normally what you want is a view with a scrollbar and or some form of collapsing related entries into categorised information. If you just want to display a list of pages where each page is X entries: use a tab widget or stacked widget.