Add a class name to element immediately this element is loaded - javascript

I have an element which has to be hidden when JavaScript is enabled. The current code seems like this:
<body>
...
<div id="js-hidden"></div>
...
<script src="jquery.js"></script>
<script>
$(document).ready(function() {
$('#js-hidden').hide();
})
</script>
There is the problem, the js-hidden div is visible since the rest of page (and JavaScripts) are loaded.
Can I hide that earlier? This solution is so bad for me, JS user can´t see this element.
PS: I've written the example with using jQuery, it can be in plain JS too, of course :-)

$(document).ready makes it happen after full page loaded you can use
<body>
...
<div id="js-hidden"></div>
...
<script src="jquery.js"></script>
<div id="js-hidden"></div>
<script>
$('#js-hidden').hide();
</script>

Simplest thing:
<style>
.js-hidden {
display: none;
}
</style>
<noscript>
<style>
.js-hidden {
display: block;
}
</style>
</noscript>

Since you cannot use onload event on div I guess the best solution is put your js right after that div...

Related

jquery load time and css styling inside it

like you see in the code below, the jquery loads a page but it seems that all the .css styling inside the jquery waits until the jquery is loaded which can take some fraction of a second if the file is big. So if I have .css("display","none") it will not work for that time causing a flickering before the styling kicks in. I have this problem only with Mozilla. The code below its only an example and it works well because is small. Some ideas how to fix this?
$(document).ready(function() {
$(".rectangle").click(function() {
$("body").load("debugging2.html", function() {
$(".rectangle").css("display","none")
$(".rectangle").fadeIn(1000);
}) ;
});
})
.rectangle{
height: 200px;
width: 200px;
background-color:#000;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<body>
<div>
<div class="rectangle"></div>
</div>
</body>
$(document).ready(function() {
$(".rectangle").click(function() {
$("head").append("<style>.rectangle{display:none;}</style>");
$("body").load("debugging2.html", function() {
$("rectangle").fadeIn(1000);
});
});
})
Since script tags are loaded synchronously (by default) they indeed block page rendering. It can result in blank unstyled page if HTML is not processed and styles are not loaded by that moment. Hence the common very simple solution is to move heavy script tags to the very end of the </body> and put necessary CSS style in the <head>.
As the result of above, CSS gets downloaded first, after HTML is loaded quickly, rendered and styled and only after that slow scripts get downloaded.
In code it will look something like this:
<head>
<link href="style.css" rel="text/css" type="stylesheet">
</head>
<body>
<div>
<div class="rectangle"></div>
</div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<!-- some other scripts -->
</body>
As the bonus, you don't need to bind to document ready event anymore ($(document).ready(function() {});), since HTML is all loaded by default, when scripts are executed.

JQuery Messed Up Page on Load

Not quite sure how to define this issue. I just started working with jQuery and Javascript and pretty much everything is fine, except for when the page initially loads. I have the page fade in, but it looks like all the CSS isn't being applied until the jQuery loads.
I tried this script in my Head tag, but it doesn't work. Help?
<script type="text/javascript">
$(function(){
$('#box-container').hide();
});
$(window).load(function() {
$("#box-container").show();
});
</script>
Whoops: site: http://www.elijahish.com
You should use a Javascript console like Chrome Console or Firefox Firebug to debug your code.
First, you are placing your script block which requires jQuery before jQuery is defined:
<head>
<script type="text/javascript">
$(function(){
$('#box-container').hide();
});
$(window).load(function() {
$("#box-container").show();
});
</script>
...
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js"></script>
...
So you would see the following (in Chrome Console):
ReferenceError: $ is not defined
$(function(){
Second, you seem to be trying to run a script which is accessing (in the first block) an element (#box-container) before it has been seen in the DOM itself. You could use jQuery.ready on that first block, but that could be messy. I would instead suggest you place this right after <div id="box-container"> is defined:
<body ...>
<div id="box-container" ...>
...
</div>
<script type="text/javascript">
(function($){
$('#box-container').hide();
$(window).load(function() {
$("#box-container").show();
});
})(jQuery);
</script>
Demo: http://jsfiddle.net/5JpVB/4 (I use a setTimeout for dramatic effect.)
Or put it directly after the <div ...> is opened:
<div id="box-container">
<script type="text/javascript">
(function($){
$('#box-container').hide();
$(window).load(function() {
setTimeout(function(){
$("#box-container").show();
}, 2000);
});
})(jQuery);
</script>
Box Container shown on window.onload.
</div>
http://jsfiddle.net/5JpVB/5/
And the coup de grâce (document.write nothwithstanding):
<head>
...
<script>
document.write('<style>#box-container{display: none;}</style>');
</script>
...
</head>
http://jsfiddle.net/5JpVB/2/
Yes, that is a script that "puts" the style display: none into the header, which "neatly" bypasses some of the conjecture that's been thrown around (there's downsides for each method, more or less). There's an elegance to this method (except, of course, using document.write, which is icky).
And yet another way, using the CSS display: none method:
<head>
...
<style>
#box-container {
display: none;
}
</style>
...
<div id="box-container">
<noscript><style>#box-container{display: block;}</style></noscript>
Box Container shown on window.onload.
</div>
http://jsfiddle.net/5JpVB/3/ (Just the Result page, disable Javascript to see it work.)
You are getting a case of FOUC : http://www.bluerobot.com/web/css/fouc.asp/
And, years later we are still plauged! http://paulirish.com/2009/avoiding-the-fouc-v3/
A variety of solutions are included on this link.
You could also set the style of your content to be hidden before running the javascript that shows the content. Jared shows you a nice way to do this.
Might I make a suggestion that you use combination of CSS and JavaScript, rather than one or the other. I had the same issue using jQueryUI on a site I'm building and found that a lot of these solutions out there would make the contact unavailable to those without JavaScript.
So here is what I did:
CSS:
.flash #wrapper {
display: none;
}
What this does is set the <div id="wrapper"> to hidden only if it is a decendent of the class flash. So to keep it from being hidden from those with out javascript I add the class flash to the <html> element. So it can only be physically hidden if the end user has JavaScript enabled, otherwise they'll at least have access via the unstylized content.
JavaScript:
$('html').addClass('flash');
$(doctument).ready(function() {
/* Do all your stuff */
/* When done show the wrapper with the content stylized */
$(#wrapper).show();
});
Depending on your pages time to load you might get a little flash, but it wont be a flash of unstylized content, which is rather ugly. In my case I had a jQueryUI menu item that would flash the normal <ul> element first then the menuUI item, and my <div> elements are resized with jQuery so that each <div> column is equal hight, but it would flash the different heights first. This fixed it while still giving accessability to none Script enabled browsers.

Javascript gracefully degrade a whole div

So on the page I have a div that's part of the layout.
The div contains JS stuff, so although it's part of the layout, there's no point in showing it if there's no Javascript.
Now I would normally put this in <head>:
<style> div#target{ display:none } <style>
<script> $(document).ready(function(){ $('div#target').show(); }); </script>
But my boss wants that div during page load.
So I have to resort to something ugly in <body>:
<style> div#target{ display:none } <style>
<div id="target">stuff in div</div>
<script> $('div#target').show(); </script>
Which is invalid xHTML, has some IE drawbacks I heard, and most of all it just sucks.
What else can I do?
Leave the <style> element in the head.
There is nothing invalid about having a <script> as a sibling element to a <div>
You could be more efficient with:
div#target{ display: none }
body.js div#target{ display: block }
and
<body>
<script> document.body.className += " js"; </script>
That said, if an element is only relevant if JS is available, then it usually makes sense to add it using JavaScript instead of trying to hide it if JS isn't available.

JavaScript question

It is possible not to show html page in user browser until some JavaScript(built-in or in separate file) will be loaded and executed(for page DOM manipulation)?
The easiest thing to do is to set the css variable
display: none;
to the whole page.
then when everything is loaded you can set the display to
display: block; // or something else that suits.
If you make sure that piece of CSS is loaded at the very start of your document it will be active before any html is shown.
if you use a javascript library like jQuery you'll have access to the $(document).ready() function, and can implement a switch over like this:
<html>
<head>
<title>test</title>
<style type="text/css">
body > div {
display: none;
}
</style>
<script type="text/javascript">
$(document).ready(function() {
$('body > div').css('display', 'block');
});
</head>
<body>
<div>
This will initially be hidden.
</div>
</body>
</html>
Not in the classical way you'd distribute a page. Browsers will (usually) start to display chunks of the base HTML file as it arrives.
Of course, you could simulate this by generating all the HTML on the fly from some included Javascript file. But that doesn't sound like a good plan as it will degrade horribly for people without JS enabled, or if you have a minor bug in your script. A better option might be to style the body tag to display: none and restyle it from the script to make certain parts visible again.
What is it you're actually trying to achieve? It sounds like there's likely to be a better way to do this...
Place the content of HTML page in a DIV, make its diplay none and on load of body diplay it.
<script type="text/javascript">
function showContent() {
var divBody=document.getElementById('divBody');
divBody.style.display= 'block';
}
</script>
<body onload="showContent()">
<div id="divBody" style="display: none;">
<--HTML of the page-->
</div>
</body>
Examples of what you might want to do:
Facebook's "BigPipe": http://www.facebook.com/notes/facebook-engineering/bigpipe-pipelining-web-pages-for-high-performance/389414033919
This method allows you to load JS first then ASYNC+inject all DOM content.
GMail
Zimbra (open-source web app similar to MS Outlook/Exchange)
My understanding is that you want to run some javascript code before you load the page. In the js file you write your init function and add the eventlistener to the window on "load" event. This will ensure that the init code gets executed first and then you can start displaying the HTML content.
var Yourdomain = {};
YourDomain.initPage = function(){
/* Your init code goes here*/
}
window.addEventListener("load", YourDomain.initPage, false);
All You really need to do is give your element an ID or CLASS and use the dislay: none; property. When your ready to show it just delete it.
CSS:
#div_1 {
display: none;
}
HTML:
<div id="div_1">
<p>This will be the hidden DIV element until you choose to display it.</p>
<p id="js_1"></p>
<script>
var x = "Some Test ";
var y = "Javascript";
document.getElementById("js_1").innerHTML = x + y;
</script>
</div>

Removing page load 'glitch' while jQuery executes

Users in my site are seeing a half-second glitch on each page before any jQuery code executes. This code manipulates the page so you can visibly see elements move in one big chunk, making the user experience feel clunky. I'd prefer the page not to display at all until the JavaScript has run.
I'm using jQuery provided by the Google API in a page as follows:
<script type="text/javascript" src="http://www.google.com/jsapi"></script>
<script type="text/javascript">
google.load("jquery", "1.3.2");
</script>
<script type="text/javascript" src="MyScript.js"></script>
In MyScript.js:
google.setOnLoadCallback(runOnLoad);
function runOnLoad() {
// Do stuff
}
Does anyone know if it's possible to run the JavaScript before the page is displayed in the browser?
You could probably add a css class to your main div that would hide the content, and then remove that class as the last thing that MyScript.js does.
In your html template:
<body>
<div id="mainContent" class="hidden">
</div>
</body>
The css class:
.hidden
{
display: none;
}
Last executed statement of MyScript.js:
$("#mainContent").removeClass("hidden");
I would agree with Jan.
Most (not all) browsers load CSS first before javascripts.
So CSS would be advisable for you.

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