Is there a javascript event I can hook into that will let me know when everything has finished drawing to the browser screen? Images, backgrounds, and DOM elements with proper CSS.
I am setting up some "loading..." divs that should disappear only when the page is perfect and ready to be shown to the user.
I am aware of $(document).ready and onLoad, but these are not what I mean.
I am using angularJS, but I dont think this should matter.
thanks!
As you may know, $(document).ready only waits for HTML structure and Javascript to load to trigger.
You better use :
$(window).load(function(){
//do stuff here
});
to wait for everything in your page to load (even pictures)
Though this solution will not trigger any event, it should help you.
Define CSS like this:
#dvLoading
{
background:#000 url(images/loader.gif) no-repeat center center;
height: 100px;
width: 100px;
position: fixed;
z-index: 1000;
left: 50%;
top: 50%;
margin: -25px 0 0 -25px;
}
Use the above in
<div id="dvLoading"></div>
And then do this:
$(window).load(function(){
$('#dvLoading').fadeOut(2000);
});
Demo: http://jsfiddle.net/jquerybyexample/ssqtH/embedded/result/
Source:http://www.jquerybyexample.net/2012/06/show-loading-image-while-page-is.html
Because you're using AngularJS, I can assume that your images and content are mostly loaded dynamically, in which case you cannot (easily) know when exactly all your content is even generated, and hence you'd also have no idea when all your images will be loaded since everything will be loaded asynchronously.
What you could do is have your DOM placeholders for widgets/apps/controllers be set to a loading-like state by default (a loading.gif maybe?) and when Angular generates the content it will just replace it. Look at http://docs.angularjs.org/guide/animations for how to implement animations on certain directives.
Then within those widgets/apps/controllers you would have to do the same thing with the content within them...
So basically it's a cascading "loading screen", where each level of your application loads up like a water fountain.
What is wrong with the $(document).ready or onLoad functionality?
$(window).load(function()
{
$(".loading").hide();
}
Related
I have a client who asked to temporarily hide all images on a webpage, but without creating a 404 (leaving them visible to bots).
My try was this:
jQuery(document).ready(function() {
jQuery("img").attr({src: "/my/path/myfile.png"});
});
The problem is that on a slow connection, images are loading, and only on $(document).ready() are hiding (of course - that is what I asked in the code :-) - I do not know a different method …)
How can I make it so that all the images will be "hidden" on browser side, while loading, in a progressive way?
Why don't you simply hide them using CSS:
img {
visibility: hidden;
}
This way all images are linked correctly, your content flow is intact (in contrary of using display: none;), you don't need any JavaScript and the users won't see them.
Demo
Try before buy
There is two ways that I know to do this.
img {
background: url('loading.gif') no-repeat;
}
and
<script>
$('#loadImg').show();
$('#BaseImage').load(function(){$('#loadImg').hide();});
</script>
You assign load event to the image which fires when image has finished loading but background image to all images using css will be easier. Take note that This doesn't work very well with transparent images.
First off, let me give you a little background. I am creating a responsive page using % for positioning my divs. It allows the user to drag and drop items wherever they please. The issue arises when the user places the object to near the edge of the page. When you resize the browser the images start to go off the page and get cut off.
#div1
{
overflow: hidden;
right: <?php variable>;
bottom: <?php variable>;
}
#div2
{
overflow: hidden;
left: <?php variable>;
top: <?php variable>;
}
What I would like to try and do is allow the percentage's to control the placement up until the edge of the page. Then I would like to hardcode the variables to something like 10px so it never goes of the page.
I thought of doing this in javascript(if statement('s)), but thought maybe there was a simpler way(css properties). Any help or suggestions would be greatly appreciated.
Thanks,
Rob
If you are going to use javascript you need to have a separate function that triggers on browser resize:
window.onresize = function(event) {
//your code here
}
or if you are using the popular jQuery
$(window).resize(function(){
//your code here
});
is the same.
If you want to hardcode it with css use a #media query:
#media(max-width:767px) { /*or whatever you want to use to trigger the css that will be used after browser size fits your problem */
.myImage {left:10px;top:10px;}
}
More info on what you can use with #media can be found here http://www.w3.org/TR/css3-mediaqueries/
If you ask me I think that you will accomplish a much more solid solution using javascript and since I suspect you are using js to drag elements around just go with it for resizing and repositioning too.
If I have a div acting as a container that when empty shows an image, and I want to remove that image when content gets added to the container dynamically, what would be the best Jquery method to accomplish this? Doing the usual -
if ($(".container").html().length <= 0) {
$('.ad').show();
}
does not work in this case since the content being added is dynamic and does not involve a refresh. I tried storing the check in in a setIntercal function that would run every 100ms but the results didn't turn out as expected and it also caused some odd flickering on the page.
EDIT**
Josh Burgess' method would be the one I use in all cases if I didn't have to support IE8. Because of this I'm going to fall back to adding a .hide() method on the when the click event for adding content is fired. Thanks for the help!
Why use jQuery at all?
Try this CSS:
div.myDiv:empty{
background-image: url(path/to/myimage);
height: 50px;
width: 50px;
}
div.myDiv {
background-image: none;
height:auto;
width: auto;
}
--EDIT--
Here's a working example in jsfiddle, and it works in reverse as well
I have a webpage which heavily makes use of jQuery.
My goal is to only show the page when everything is ready.
With that I want to avoid showing the annoying page rendering to the user.
I tried this so far (#body_holder is a wrapper inside body):
$(function(){
$('#body_holder').hide();
});
$(window).load(function() {
$("#body_holder").show();
});
This works completely fine, but messes up the layout.
The problem is that hiding the wrapper interferes with the other jQuery functions and plugins used (eg layout-plugin).
So I guess there must be another trick to do this. Maybe lay a picture or div over the body until window.load has occurred?
What approaches do you use?
EDIT:
The solution most likely has to be another way than display:none or hide();
Anything done with jQuery will normally have to wait for document.ready, which is too late IMHO.
Put a div on top, like so:
<div id="cover"></div>
set some styles:
#cover {position: fixed; height: 100%; width: 100%; top:0; left: 0; background: #000; z-index:9999;}
and hide it with JS when all elements are loaded:
$(window).on('load', function() {
$("#cover").hide();
});
Or if for some reason your script uses even longer time then the DOM elements to load, set an interval to check the type of some function that loads the slowest, and remove the cover when all functions are defined!
$(window).on('load', function() {
$("#cover").fadeOut(200);
});
//stackoverflow does not fire the window onload properly, substituted with fake load
function newW()
{
$(window).load();
}
setTimeout(newW, 1000);
#cover {position: fixed; height: 100%; width: 100%; top:0; left: 0; background: #000; z-index:9999;
font-size: 60px; text-align: center; padding-top: 200px; color: #fff;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<ul>
<li>This</li>
<li>is</li>
<li>a</li>
<li>simple</li>
<li>test</li>
<li>of</li>
<li>a</li>
<li>cover</li>
</ul>
<div id="cover">LOADING</div>
Here is a jQuery solution for those looking:
Hide the body with css then show it after the page is loaded:
CSS:
html { visibility:hidden; }
JavaScript
$(document).ready(function() {
document.getElementsByTagName("html")[0].style.visibility = "visible";
});
The page will go from blank to showing all content when the page is loaded, no flash of content, no watching images load etc.
You should try setting visibility to hidden instead of display:none. Setting visibility to hidden will retain all elements positions and dimensions, thus it shouldn't create layout problems.
Start your HTML with:
<body style="opacity:0;">
At the end of your script:
document.body.style.opacity = 1;
Stumbled upon this and tried #9ete's solution but it didn't help me.
This worked instead:
CSS:
html { visibility:hidden; }
JS:
window.addEventListener('load', function () {
document.getElementsByTagName("html")[0].style.visibility = "visible";
});
As per documentation for window, the load event is fired after all the content (images included) is loaded while $document says that ready is fired after only the DOM is ready.
Your question is valid, but I would not get in a practice of hiding or covering the page while things are spinning up.
It keeps the user from understanding what's happening on the page. While lots of things may need to load, different parts of the page should spring to life as they're loaded. You should get in the practice of locking controls that are not ready, perhaps displaying a spinner or some other progress indicator over them. Or setting the cursor to wait on loading items.
This keeps the user in the loop and allows him to see and interact with parts as they come online instead of obscuring all parts until everything is ready.
You will normally want to load the things the user needs the quickest access to, usually stuff above the fold, first. Loading is a prioritization that can easily be coordinated with Promises.
At the very least seeing the page allows the user to get his bearings and decide what to do. Be transparent.
I was seeking a non-javascript solution so I found one that is working on most browsers in acceptable manner.
Since the loading order of CSS rules matters;
Define the hiding class in the first CSS file or inline in head.
.hidden-onpage-load{ display: none; }
In the body, the class can be used as
<div class="hidden-onpage-load"> ... </div>
Redefine it inline or in a CSS file after all other CSS and JS files are loaded
.hidden-onpage-load{ display: block; }
The simplest solution I've come up with is to wrap the body in a as suggested previously, but set it as hidden from the get go, then use JQuery (or javascript) to unhide on load after all components are loaded.
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="bodyDiv" hidden>
Hello World!
</div>
<script>
$(document).ready(function() {
// add JQuery widget loads here
$("#bodyDiv").show(); // reveal complete page
})
</script>
Don't forget, a lot of frameworks use javascript to structure a page. To prevent the page from showing before these modification have been made you'll need to do something like what is described here (e.g. run a script at the end of the page to show the real contents of the page):
Detect if any JavaScript function is running
If you have a div #bodyholder then you can put display:none in your CSS for it and then with jQuery do:
$(document).ready(function() {
$('#body_holder').show();
});
I don't see why hiding a div should interfere with the loading of anything, because all it means is it is hidden. However, if you have lots of jQuery being used then make sure you wrap it in $(document).ready which will make sure that the DOM is fully loaded before the Javascript is executed
A further point is that HTML/CSS is designed for progressive loading, and if you do it properly then you can get a nice progressive loading of content for your users. I personally wouldn't want my users getting a white screen for a few seconds until everything was loaded. Move your Javascript to the end of the page so that it doesn't block loading and get content onto the screen as quickly as possible.
I have a screen in which there are different functions. There is a dropdown box onchange of which an Ajax call goes and a jsp page is returned in response. This response i then put inside a div below my dropdown box.
Now what i want is that untill this jsp is not filled in the div element the screen is blocked either by an alert box or some other dialog box.
How can i achieve this ?
You can use blockui jquery plugin from here. Call blockUI before making ajax call and unblockUI in your ajax callback.
#linusunis fed,
If you want to prevent the user from clicking on anything I suggest overlaying a div element & maybe making it semi-transparent. Below is CSS for the div & jQuery code to animate displaying the screen overlay and removing the screen overlay. Just call "block_screen" when you make your call & "unblock_screen" after you received the data & placed your new div on the page. This is just off the top of my head so you may need to double check for errors but it looks good to me.
You need to include jQuery on the page for this to work. Download it here: http://code.jquery.com/jquery-1.7.1.min.js
<style type="text/css">
.blockDiv {
position: absolute:
top: 0px;
left: 0px;
background-color: #FFF;
width: 0px;
height: 0px;
z-index: 10;
}
</style>
<script type="text/javascript" language="javascript">
function block_screen() {
$('<div id="screenBlock"></div>').appendTo('body');
$('#screenBlock').css( { opacity: 0, width: $(document).width(), height: $(document).height() } );
$('#screenBlock').addClass('blockDiv');
$('#screenBlock').animate({opacity: 0.7}, 200);
}
function unblock_screen() {
$('#screenBlock').animate({opacity: 0}, 200, function() {
$('#screenBlock').remove();
});
}
</script>
I would use Jquery and Jquery UI. Jquery UI provides a modal dialog in which you could place a loading message that will keep the user from clicking elsewhere on the screen.
http://jqueryui.com/demos/dialog/#modal
If you actually want to block the UI, just make the AJAX request synchronous.
Just use a boolean flag, which until is set (on receiving content), you lock the functionality. And once this flag is set, proceed further. Assuming you do have control over those functions.
you can use a div, along with z-index, opacity and cursor styling. although I don't know you application, blocking the entire page doesn't sound like a great user experience to me. perhaps you could place the div only over the affected area of the page