Embedding dynamically sized webpage with javascript - javascript

Okay, so first some background info: I am trying to embed a webpage within another page. The sub-page is basically a small web application written in javascript and html that takes in several screens of input (radio buttons, text boxes, etc.) and gives a screen with results at the end. Each of these screens can be a different size.
There are two methods I have tried using to do the embedding:
1) Copy all of the html and javascript from the sub-page into the main page and stick it in a div/table/whatever.
2) Keep the sub-page in its own file and embed it using embed/object/iframe.
Using the first method the page behaves as it should; the only real problem (aside from being kind of a messy solution) is that the sub-page I am embedding is actually generated by an external application, and every so often the page is replaced with a newer version. This more or less rules out using the first method as a long-term solution.
Now the second method has its own problems. Since the embedded javascript page changes in height, the frame that is holding it needs to vary in size with it. I'm able to change the size using any of the solutions given here, however these do not update the size of the frame as the user progresses through each screen.
The closest solution I've been able to come up with so far is using a document.onclick handler to catch any clicking which might cause the next screen of the sub-page to come along. The handler pauses for a very short time (to allow the next screen to come up) and then calls the necessary resizing function. However this feels like a very hacky solution, and there is also a slightly noticeable delay during with the scroll bar shows up on the side of the frame when it hasn't expanded yet to fit the new content. I'm thinking there must be a better way to do this.

If the file is on the same server/domain, you could just load it in with jQuery. Here is some jQuery code:
<script type="text/javascript">
$(document).ready(function() {
$('#id-of-div').load('/path/to/page.html');
});
</script>
Just change id-of-div to the id of the div that you want the page to be loaded into and change /path/to/page.html to the actual URL to the page. (you don't need the domain of it, just the path to it)
I hope this helps.
If this answers your question, please remember to click the checkmark next to this to accept this answer.

Related

Google page speed issue with "Prioritize visible content"

In Google Page speed I receive a comment to "Prioritize visible content" this appears to be a recent change to the page speed algorithm. In order to try and understand the problem, I created a simple page with only one image and nothing else in the HTML (under my domain), and I still see the same message to "prioritize visible content."
The only way I found to eliminate the error was to convert the image to Base64 and place the image inside the HTML. I think this is not a good solution to the problem, as it will make the HTML heavy and slow the page down.
Are there any other suggestions to solve this problem? Thanks
Usualy this issue shows when you have a lot of external javascript or css files needed by your page to render properly. The ideal solution that eliminates the issue is when you have images and css neded for "above the fold" part of your page placed inline in your HTML document. This allows browser to render visible part of the page immediatelly without making additional requests.
There are different ways how you can achieve this. One way is to load all your css and js asynchronously and inline part of css and js neded for "above the fold" area.
The reason why this issue appears in your test case could be that image takes comparable time to load to the HTML page itself.
You can read more about possible fixes in google documentation on this issue https://developers.google.com/speed/docs/insights/PrioritizeVisibleContent?hl=en

Is it possible to direct which elements of a page are painted first by the browser?

I wanted to know if there was any way to control browser painting, for example I'd like to load elements at the top of the page first so users can see content straightaway. The elements at the bottom of the page can load last as the user will not see them until they scroll down.
I'm looking to optimize my site which currently has a 6 second load time and I'd like to get it down to 1 second. This is mostly being caused by JS and images. I know that reducing both these will mean I wont need to worry about directing the painting but out of interest I just wanted to know if it was possible?
Apologies if my understanding of browser painting is very basic
its not that difficult. all you need is ajax. load the inital markup and then load the rest of the page via ajax.
just load the page with little markup which you initally want to show to the user. then as user scrolls down you can make ajax calls and get xml or json or also html files and render them on you page, for example:
$(window).on( "scroll" , function() {
var $document = $(document);
var $window = $(this);
if( $document.scrollTop() >= $document.height() - $window.height() - 400 ) {
//make ajax call here and load the data
}
});
Also read this
After looking into this further I found this article
http://www.feedthebot.com/pagespeed/prioritize-visible-content.html
which provides a good way of directing which parts of the page are rendered first. By separating your content in to above and below the fold content you can decide what needs to be delivered first i.e. your main content rather than sidebar ads. Using inline style to display your above-the-fold content will make it appear very quickly since it won't need to wait for for an external request.
But this is only good for simple CSS, if pages require complex CSS then it's better to use an external file because:
"When you use external CSS files the entire file is cached (remembered) by the browser so it doesn't have to take the same steps over and over when a user goes to another page on your website. When you inline your CSS, this does not occur and the CSS is read and acted upon again when a visitor goes to another page of your website. This does not matter if your CSS is small and simple. If your CSS is large and complex, as they often tend to be, then you may want to consider that the caching of your CSS is a better choice."
http://www.feedthebot.com/pagespeed/inline-small-css.html

What is the cleanest way to disable postback controls until the page has fully loaded?

I have a website that has some intense graphics, and people with slow connections might require download time. While their browser is downloading, they have form options. And a lot of times they will fill the form out and hit submit.
This causes an event validation issue, because the page wasn't fully loaded. I can think of a lot of ways off the top of my head to fix this. I could go back and disable every single control, and then write javascript to enable these controls clientside when the page is loaded.
I also looked into blockui, but it will block the whole page or just a div. I am looking for something I can stick in my masterpage and forget about it.
Any ideas?
It seems like the correct approach would be to load in your intense graphics after-the-fact, so that users can still submit forms as soon as the critical DOM elements are rendered. (I'm assuming it's not vitally important that all the images be loaded before the form gets submitted?)
You could do this fairly easily by causing your images to be loaded as CSS-based backgrounds on div and body elements, based on a specific class, like this:
body.loaded {background: black url("http://us.battle.net/sc2/static/images/layout/body-bg-baked.jpg") center top no-repeat;}
Then have the following code to add that class after the page loads:
$(window).load(function() {$('body').addClass('loaded');});
It shouldn't produce any significant slow-down in the loading of the images, but it will allow all your page's DOM elements and javascript to run while those images are downloading if necessary.
(jsFiddle example)
I couldn't explain the answer myself. But I think this has the gist of what you need to do.
http://www.telerik.com/community/forums/aspnet/ajax/disable-or-gray-out-page-when-displaying-loading-panel.aspx

Best practice for injecting a header or toolbar into a page?

Our webapp allows customers to view historical snapshots of pages on their site. We want to inject a header into the top of the page (something like the digg or linkedin toolbar) that contains data like snapshot time, url, and various other metrics.
We want to present these pages as close as possible to their original state.
So what is the best way to add a header into a page whilst preserving it as best possible?
Potential approaches we have looked at:
Sticking the cached page in an iframe. However a surprising number of sites contain frame-breaking code and we don't want to do anything hacky like trying to stop this.
Add an absolutely/fixed positioned div to the top of the page with a high z-index. The problem with this approach is that a) some of your styling may get over-written, b) javascript that runs on DOM load can screw around with your html/ccs (e.g Plone-powered sites add classes and styles to all tables for example) c) the varying DOCTYPEs or lack-of can screw up our css (yes IE, looking at you).
Adding an absolutely positioned iframe to the top of the page with a high z-index. This get around any of our html/css being clobbered or amended. However again we have DOCTYPE issues - we'd like it statically positioned and IE7 doesn't support this in Quirksmode.
Any thoughts? Thanks
Why would you want to use a banner with a height of 100px? I see some other possibilities:
Can't you use a link to a popup or page with more information?
Or make it pull out if you hover it.
That way it will not obscure a large percentage of the site.
If you control the links that lead to an archived version, you could put in a proxy-url. Let that URL open the right html in a frame. This is much like google cache:
show a list of links that look like pagearchive.html?version=43234324
let pagearchive.html be a html page with an iframe that starts 100px from the top. the version=43234324 part can let you open the right url in the frame.

How can I make the browser wait to display the page until it's fully loaded?

I hate how you can actually see webpages load. I think it'd be much more appealing to wait until the page is fully loaded and ready to be displayed, including all scripts and images, and then have the browser display it. So I have two questions:
How can I do this?
Is this common practice? If not, why?
This is a very bad idea for all of the reasons given, and more. That said, here's how you do it using jQuery:
<body>
<div id="msg" style="font-size:largest;">
<!-- you can set whatever style you want on this -->
Loading, please wait...
</div>
<div id="body" style="display:none;">
<!-- everything else -->
</div>
<script type="text/javascript">
$(document).ready(function() {
$('#body').show();
$('#msg').hide();
});
</script>
</body>
If the user has JavaScript disabled, they never see the page. If the page never finishes loading, they never see the page. If the page takes too long to load, they may assume something went wrong and just go elsewhere instead of *please wait...*ing.
I think this is a really bad idea. Users like to see progress, plain and simple. Keeping the page at one state for a few seconds and then instantly displaying the loaded page will make the user feel like nothing is happening and you are likely to lose visits.
One option is to show a loading status on your page while stuff processes in the background, but this is normally reserved for when the site is actually doing processing on user input.
http://www.webdeveloper.com/forum/showthread.php?t=180958
The bottom line, you at least need to show some visual activity while the page is loading, and I think having the page load in little pieces at a time is not all that bad (assuming you aren't doing something that seriously slows down page load time).
There is certainly a valid use for this. One is to prevent people from clicking on links/causing JavaScript events to occur until all the page elements and JavaScript have loaded.
In IE, you could use page transitions which mean the page doesn't display until it's fully loaded:
<meta http-equiv="Page-Enter" content="blendTrans(Duration=.01)" />
<meta http-equiv="Page-Exit" content="blendTrans(Duration=.01)" />
Notice the short duration. It's just enough to make sure the page doesn't display until it's fully loaded.
In FireFox and other browsers, the solution I've used is to create a DIV that is the size of the page and white, then at the very end of the page put in JavaScript that hides it. Another way would be to use jQuery and hide it as well. Not as painless as the IE solution but both work well.
Here's a solution using jQuery:
<script type="text/javascript">
$('#container').css('opacity', 0);
$(window).load(function() {
$('#container').css('opacity', 1);
});
</script>
I put this script just after my </body> tag. Just replace "#container" with a selector for the DOM element(s) you want to hide. I tried several variations of this (including .hide()/.show(), and .fadeOut()/.fadeIn()), and just setting the opacity seems to have the fewest ill effects (flicker, changing page height, etc.). You can also replace css('opacity', 0) with fadeTo(100, 1) for a smoother transition. (No, fadeIn() won't work, at least not under jQuery 1.3.2.)
Now the caveats: I implemented the above because I'm using TypeKit and there's an annoying flicker when you refresh the page and the fonts take a few hundred milliseconds to load. So I don't want any text to appear on the screen until TypeKit has loaded. But obviously you're in big trouble if you use the code above and something on your page fails to load. There are two obvious ways that it could be improved:
A maximum time limit (say, 1 second) after which everything appears whether the page is loaded or not
Some kind of loading indicator (say, something from http://www.ajaxload.info/)
I won't bother implementing the loading indicator here, but the time limit is easy. Just add this to the script above:
$(document).ready(function() {
setTimeout('$("#container").css("opacity", 1)', 1000);
});
So now, worst-case scenario, your page will take an extra second to appear.
Immediately following your <body> tag add something like this...
<style> body {opacity:0;}</style>
And for the very first thing in your <head> add something like...
<script>
window.onload = function() {setTimeout(function(){document.body.style.opacity="100";},500);};
</script>
As far as this being good practice or bad depends on your visitors, and the time the wait takes.
The question that is stil left open and I am not seeing any answers here is how to be sure the page has stabilized. For example if you are loading fonts the page may reflow a bit until all the fonts are loaded and displayed. I would like to know if there is an event that tells me the page is done rendering.
Also make sure the server buffers the page and does not immediately (while building) stream it to the client browser.
Since you have not specified your technology stack:
PHP: look into ob_start
ASP.NET: make sure Response.BufferOutput = True (it is by default)
obligatory: "use jQuery"
I've seen pages that put a black or white div that covers everything on top of the page, then remove it on the document.load event. Or you could use .ready in jQuery That being said, it was one of the most anoying web pages I've ever seen, I would advise against it.
in PHP-Fusion Open Source CMS, http://www.php-fusion.co.uk, we do it this way at core -
<?php
ob_start();
// Your PHP codes here
?>
YOUR HTML HERE
<?php
$html_output = ob_get_contents();
ob_end_clean();
echo $html_output;
?>
You won't be able to see anything loading one by one. The only loader will be your browser tab spinner, and it just displays everything in an instant after everything is loaded. Give it a try.
This method is fully compliant in html files.
You can hide everything using some css:
#some_div
{
display: none;
}
and then in javascript assign a function to document.onload to remove that div.
jQuery makes things like this very easy.
In addition to Trevor Burnham's answer if you want to deal with disabled javascript and defer css loading
HTML5
<html class="no-js">
<head>...</head>
<body>
<header>...</header>
<main>...</main>
<footer>...</footer>
</body>
</html>
CSS
//at the beginning of the page
.js main, .js footer{
opacity:0;
}
JAVASCRIPT
//at the beginning of the page before loading jquery
var h = document.querySelector("html");
h.className += ' ' + 'js';
h.className = h.className.replace(
new RegExp('( |^)' + 'no-js' + '( |$)', 'g'), ' ').trim();
JQUERY
//somewhere at the end of the page after loading jquery
$(window).load(function() {
$('main').css('opacity',1);
$('footer').css('opacity',1);
});
RESOURCES
CSS delivery optimization: How to defer css loading?
What is the purpose of the HTML "no-js" class?
How to get the <html> tag HTML with JavaScript / jQuery?
How to add/remove a class in JavaScript?
While I agree with the others that you should not want it I'll just briefly explain what you can do to make a small difference without going all the way and actually blocking content that is already there -- maybe this will be enough to keep both you and your visitors happy.
The browser starts loading a page and will process externally located css and js later, especially if the place the css/js is linked is at the 'correct' place. (I think the advice is to load js as late as possible, and to use external css that you load in the header). Now if you have some portion of your css and/or js that you would like to be applied as soon as possible simply include that in the page itself. This will be against the advice of performance tools like YSlow but it probably will increase the change of your page showing up like you want it to be shown. Use this only when really needed!
You could start by having your site's main index page contain only a message saying "Loading". From here you could use ajax to fetch the contents of your next page and embed it into the current one, on completion removing the "Loading" message.
You might be able to get away with just including a loading message container at the top of your page which is 100% width/height and then removing the said div on load complete.
The latter may not work perfectly in both situations and will depends on how the browser renders content.
I'm not entirely sure if its a good idea. For simple static sites I would say not. However, I have seen a lot of heavy javascript sites lately from design companies that use complex animation and are one page. These sites use a loading message to wait for all scripts/html/css to be loaded so that the page functions as expected.
Don't use display:none. If you do, you will see images resize/reposition when you do the show(). Use visibility:hidden instead and it will lay everything out correctly, but it just won't be visible until you tell it to.
Hope this code will help
<html>
<head>
<style type="text/css">
.js #flash {display: none;}
</style>
<script type="text/javascript">
document.documentElement.className = 'js';
</script>
</head>
<body>
<!-- the rest of your code goes here -->
<script type="text/javascript" src="/scripts/jquery.js"></script>
<script type="text/javascript">
// Stuff to do as soon as the body finishes loading.
// No need for $(document).ready() here.
</script>
</body>
</html>
Put text at the top of the page. While the user reads it, the rest of the page can load and it will be ready by the time the user scrolls down.
I am, frankly, a bit disturbed at many of the answers here. I'd say all of them are terrible. Although I share the skeptical reaction of the various top respondents, many answers give "solutions" that won't display anything at all to a user who has JavaScript disabled, and many others rely on a customized on-page loading notice, while signaling to the browser that the page is already loaded.
As a user, I hate both of these outcomes, so as a web-developer, I'd say these are both "non-solutions". You never want to anger your userbase and the solutions given here will anger a lot of users. I especially hate these approaches because if the user opens a webpage in the background in a new tab, the browser will display the page as loaded but the user might click over to it to find that it isn't loaded.
Independently of your question here, best practice is to make as much of your site work without JavaScript as possible, and best practice is to use the browser's built-in loading signals and never signal to the browser that the page is loaded before it actually is. So really, the only good way to do this is to make your page load so fast that there is never any moment of the user waiting.
The best way to achieve what you want is avoid use of Javascript to load elements of the page, and then optimize the page intensely. Here are the components of this approach:
Have JavaScript on the page if you like, but don't use it to load or otherwise modify any DOM elements after the initial request is fulfilled by the server. Use JavaScript to modify elements of the page only later, such as if triggered by user input, or perhaps to refresh an element after some time, but not in any way related to the page's initial loading. I.e. use JavaScript for what it was designed for (to make webpages interactive) and don't use it to do what HTML was designed for (to make the webpage in the first place.)
Avoid the use of any heavy JavaScript libraries and include as little JavaScript as possible. Never include JavaScript files generically, i.e. only include specific files / libraries in specific pages where you need them.
Specify the width and height of any images in the page code itself, so that the browser can know the exact layout before the image loaded. This reduces any "choppiness" as the page loads, i.e. elements moving around as the browser resizes the boxes in which images of unspecified width are contained.
Ensure that image files are in the exact dimensions being displayed on the page and are not being downsized by the browser. This minimizes file size and also minimizes CPU work the user's computer needs to do to resize images, both of which can affect load time.
Optimize the compression of images, which includes using a good lossy format like JPG and lowering the compression level to as low as you can go without affecting perception. Use lossless formats like PNG only where necessary and ideally keep them small in dimension so the filesize is also small.
Focus the intensity of your optimization efforts on any elements that load "above the fold" on a typical page, as these are what is going to affect what the user sees. Users rarely scroll down instantly, so if elements lower down on the page load a bit slower, almost no one will notice. But still optimize these lower elements reasonably because they also affect server load, bandwidth, and user CPU load.
If you use any elements at all in your page that are potentially very slow to load due to reasons beyond your control, such as content pulled from another server (ads, social media widgets, integrations with other websites, etc.), compartmentalize these in an element of fixed size, and ideally place it below the fold.
Avoid auto-ads, page-modifying AI (like Ezoic), or any other external add-ins that necessarily breaks or undermines one or more of these recommendations. For example, auto-ads are terrible because they rely on loading an external resource,they usually have heavy javascript libraries, and they also modify the page layout. Even the best-designed auto-ads are going to completely undermine all your other optimization efforts.
If you are running a company with multiple developers, quickly jettison any developers who are not fully committed to a lightweight, fast-loading web design. Ideally, don't ever hire such people to begin with. A lot of people get really vested in a certain philosophy or style of development that is at odds with lightweight design. The world would be a better place if these people were in a different line of work, rather than designing webpages.
So you've optimized your page.
This produces the outcome that, if the user clicks the link directly, they'll see the content above the fold fully loaded immediately or nearly-immediately, worst-case-scenario being that a couple images fill in in a second or two. By the time they scroll down, everything else will already be loaded. Any truly-slow-to-load content, such as Google Analytics tracking or other third-party services, will not be central to the appearance of the webpage itself, so the user will see a fully-loaded page even if there are still a few invisible elements loading behind the scenes.
On the other hand, if the user loads the link in a background tab, it will display as loading to the browser, showing the animated symbol in the tab, until it is truly fully loaded. Once it displays as loaded in the tab, if they click it, it will be fully loaded.
In addition, you will have made the page load really fast, which is a good thing in and of itself.
This is a win-win. The user sees a full-loaded page nearly instantly, there is almost never any waiting while looking at a half-displayed page, the loading symbol works as expected when loading a tab in the background, and on top of this you've netted a ton of side-benefits like reduced bandwidth and server CPU load, not to mention lessening the load on the user's CPU as well. (Many users HATE when your page cranks their CPU, and rightfully so.)
So yeah, your choice what to do, but there is only one real solution here and it is lightweight, efficient web design.

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