I am using progressive enhancement to build a website. This includes menu, slideshow, etc. The items are included in the page as unordered lists, then JavaScript applies the formatting.
My concern: how can I avoid the flash of unformatted content, where the unordered lists are visible before the formatting is applied? Are there best practices for this?
Important: the site must remain SEO friendly and accessible (this is why I am using progressive enhancement in the first place). So for example it is out of question to set the initial style of the unordered lists to display:none.
Use CSS for formatting instead of JavaScript.
So for example it is out of question to set the initial style of the unordered lists to display:none.
You can indirectly cause the style to get set to display: none when you detect JavaScript is available by using CSS and some script run before any of the content is included:
<head>
<style type="text/css">
body.withjs #menu { display: none; }
</style>
</head>
<body>
<script type="text/javascript">
document.body.className= 'withjs';
window.onload= function() {
...do stuff with menu...
document.getElementById('menu').style.display= 'block';
};
</script>
...
<ul id="menu">
...
</ul>
</body>
Related
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.
I have a blog with annotated references like [1] that.
[1]Jake Smith. http://example.com ..............
[2].............
I want it so the [1] in the text is an anchor that links to the [1] in the References. I know I could do this by doing something in the text like [1]and then making every list item in the references have an id, , that is, that is,
<ol>
<li id="ref1"></li>
...
</ol>
But that's a lot of work for me to go through all the blog posts. I'm sure I could make a JavaScript or jQuery function to add this functionality, but then it would not work with JavaScript disabled. So is there some other function I don't know? Like some fancy CSS trick, or should I just use JavaScript to do this?
What are your recommendations?
You could have the links inline so it displays normally when the user has JavaScript disabled. With JavaScript on, just style it as a Wikipedia reference.
Demo: http://jsfiddle.net/6A8nX/
Your options are:
A blog plugin that detects this in the content and forms the link and adds the related id to the appropriate element for you when the HTML is being output
A script that runs and does the same thing after the HTML has loaded.
Manually adding the links by hand.
A blog plugin is your best bet, since surely this is a solved problem (though it would depend on your blogging platform, of course).
CSS is for styling, it can't add links/ids.
In addition, remember that if you are ever going to display multiple blog posts on each page, you will want to add the blog id to the anchor as well. Instead of ref1, you'll want:
ref_[blogid]_[refid]
JavaScript and CSS are the way to go, if you cannot do this on the server side. The following will do what you want:
<html>
<head>
<style type="text/css">
ref {
display:none;
vertical-align:super;
font-size:small;
}
references {
display:block;
}
</style>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js" language="javascript"></script>
<script language="javascript">
window.onload = function(){
$("references").append("<ol>");
$("ref").each(function(index) {
$("references").append("<li><a name=\"ref_"+(index+1)+"\">"+$(this).text()+"</a></li>");
$(this).html("["+(index+1)+"]");
$(this).css("display", "inline"); // hides references unless the script runs
});
$("references").append("</ol>");
}
</script>
</head>
<body>
<p>This is a reference.<ref>http://www.google.com</ref></p>
<p>This is a another reference.<ref>http://www.yahoo.com</ref></p>
<references>
</references>
</body>
</html>
CSS is for presentation, and does not provide logic. Javascript is the best answer in this case, because it provides the tools and logic you need to accomplish the task.
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>
So I was thinking a simple way to deal with javascript being disabled by the browser would be the following:
<head>
<title>JavaScript Test</title>
<noscript>
<meta http-equiv="Refresh"
content="1;url=nojs.html" />
</noscript>
</head>
And having the nojs.html have something like:
<p>Return to test after enabling javascrpt.</p>
At the crash page.
This isn't my preferred method, but it's nice and simple until something more graceful can be worked out for users without javascript.
However, it is not valid to put a <noscript> element in the head section. The preliminary tests worked anyway, of course, but I'm superstitious when it comes to my code being valid, plus I'd hate for this to actually fail a field test.
So is there a valid way to do this? Perhaps wrapping the noscript in another element, like an object tag? Or some even simpler way I'm not thinking of?
I am not sure why you need to redirect to another page instead of just showing a message. I use JS and a little CSS to handle these situations for me. Something like this:
<head>
....
<script type="text/javascript"> document.documentElement.className += " js"</script>
<link rel="stylesheet" type='text/css' href="css/layout.css" media="all" />
</head>
<body>
<div id="noscript">Please enable JavaScript, then refresh this page. JavaScript is required on this site</div>
<div id="wrapper">
...
</div>
</body>
Then in layout.css:
#wrapper { display: none } /* Hide if JS disabled */
.js #wrapper { display: block } /* Show if JS enabled */
.js #noscript { display: none } /* Hide if JS enabled */
By doing it this way, the class is applied to the html element before the page is rendered so you won't get a flicker as the non-JS content is swapped out for the JS content.
Doug's solution is pretty good, but it has a few drawbacks:
It is not valid to have a class attribute on the html element. Instead, use the body.
It requires that you know what display type to set the element to (i.e. ".js #wrapper { display: block }").
A simpler, more valid and flexible solution using the same approach could be:
<html>
<head>
<!-- put this in a separate stylesheet -->
<style type="text/css">
.jsOff .jsOnly{
display:none;
}
</style>
</head>
<body class="jsOff">
<script type="text/javascript">
document.body.className = document.body.className.replace('jsOff ','');
</script>
<noscript><p>Please enable JavaScript and then refresh the page.</p></noscript>
<p class="jsOnly">I am only shown if JS is enabled</p>
</body>
</html>
With this, it's valid html (no class attribute on the html element). It is simpler (less CSS). It's flexible. Just add the "jsOnly" class to any element that you want to only display when JS is enabled.
The <noscript> tag cannot be in the <head>, it must be in the <body>
The common practice is to show a message instead of redirecting, as there is no way to redirect only if javascript is disabled.
You could do it the other way around, have the first page be nojs.html, and on that page use javascript to redirect to the main content.
If you truly want a valid way to do it, make your main page the nojs.htm page and use JS to hide all content before it's shown to the user and immediately redirect to the real main page using javascript.
I like Doug's solution. However, if you need to redirect, I would remember that while there is a spec and a standard, the world of web browsers is a dirty, imperfect world. Whether or not something is allowed by the spec is not as important as whether or not it works in the set of browsers you care about.
Just look at the source code of any major site... Most of them won't validate I'd bet :)
What about:
noscript{
z-index:100;
position:absolute;
top:0;
left:0;
width:100%;
height:100%;
min-height:1024px; background:#FFF;
}
And:
<noscript>
<p>Please enable Javascript on your browser.</p></noscript>
Is there a tag in HTML that will only display its content if JavaScript is enabled? I know <noscript> works the opposite way around, displaying its HTML content when JavaScript is turned off. But I would like to only display a form on a site if JavaScript is available, telling them why they can't use the form if they don't have it.
The only way I know how to do this is with the document.write(); method in a script tag, and it seems a bit messy for large amounts of HTML.
Easiest way I can think of:
<html>
<head>
<noscript><style> .jsonly { display: none } </style></noscript>
</head>
<body>
<p class="jsonly">You are a JavaScript User!</p>
</body>
</html>
No document.write, no scripts, pure CSS.
You could have an invisible div that gets shown via JavaScript when the page loads.
I don't really agree with all the answers here about embedding the HTML beforehand and hiding it with CSS until it is again shown with JS. Even w/o JavaScript enabled, that node still exists in the DOM. True, most browsers (even accessibility browsers) will ignore it, but it still exists and there may be odd times when that comes back to bite you.
My preferred method would be to use jQuery to generate the content. If it will be a lot of content, then you can save it as an HTML fragment (just the HTML you will want to show and none of the html, body, head, etc. tags) then use jQuery's ajax functions to load it into the full page.
test.html
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<script type="text/javascript" charset="utf-8">
$(document).ready(function() {
$.get('_test.html', function(html) {
$('p:first').after(html);
});
});
</script>
</head>
<body>
<p>This is content at the top of the page.</p>
<p>This is content at the bottom of the page.</p>
</body>
</html>
_test.html
<p>This is from an HTML fragment document</p>
result
<p>This is content at the top of the page.</p>
<p>This is from an HTML fragment document</p>
<p>This is content at the bottom of the page.</p>
First of all, always separate content, markup and behaviour!
Now, if you're using the jQuery library (you really should, it makes JavaScript a lot easier), the following code should do:
$(document).ready(function() {
$("body").addClass("js");
});
This will give you an additional class on the body when JS is enabled.
Now, in CSS, you can hide the area when the JS class is not available, and show the area when JS is available.
Alternatively, you can add no-js as the the default class to your body tag, and use this code:
$(document).ready(function() {
$("body").removeClass("no-js");
$("body").addClass("js");
});
Remember that it is still displayed if CSS is disabled.
I have a simple and flexible solution, somewhat similar to Will's (but with the added benefit of being valid html):
Give the body element a class of "jsOff". Remove (or replace) this with JavaScript. Have CSS to hide any elements with a class of "jsOnly" with a parent element with a class of "jsOff".
This means that if JavaScript is enabled, the "jsOff" class will be removed from the body. This will mean that elements with a class of "jsOnly" will not have a parent with a class of "jsOff" and so will not match the CSS selector that hides them, thus they will be shown.
If JavaScript is disabled, the "jsOff" class will not be removed from the body. Elements with "jsOnly" will have a parent with "jsOff" and so will match the CSS selector that hides them, thus they will be hidden.
Here's the code:
<html>
<head>
<!-- put this in a separate stylesheet -->
<style type="text/css">
.jsOff .jsOnly{
display:none;
}
</style>
</head>
<body class="jsOff">
<script type="text/javascript">
document.body.className = document.body.className.replace('jsOff','jsOn');
</script>
<noscript><p>Please enable JavaScript and then refresh the page.</p></noscript>
<p class="jsOnly">I am only shown if JS is enabled</p>
</body>
</html>
It's valid html. It is simple. It's flexible.
Just add the "jsOnly" class to any element that you want to only display when JS is enabled.
Please note that the JavaScript that removes the "jsOff" class should be executed as early as possible inside the body tag. It cannot be executed earlier, as the body tag will not be there yet. It should not be executed later as it will mean that elements with the "jsOnly" class may not be visible right away (as they will match the CSS selector that hides them until the "jsOff" class is removed from the body element).
This could also provide a mechanism for js-only styling (e.g. .jsOn .someClass{}) and no-js-only styling (e.g. .jsOff .someOtherClass{}). You could use it to provide an alternative to <noscript>:
.jsOn .noJsOnly{
display:none;
}
In the decade since this question was asked, the HIDDEN attribute was added to HTML. It allows one to directly hide elements without using CSS. As with CSS-based solutions, the element must be un-hidden by script:
<form hidden id=f>
Javascript is on, form is visible.<br>
<button>Click Me</button>
</form>
<script>
document.getElementById('f').hidden=false;
</script>
<noscript>
Javascript is off, but form is hidden, even when CSS is disabled.
</noscript>
You could also use Javascript to load content from another source file and output that. That may be a bit more black box-is than you're looking for though.
Here's an example for the hidden div way:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style>
*[data-when-js-is-on] {
display: none;
}
</style>
<script>
document.getElementsByTagName("style")[0].textContent = "";
</script>
</head>
<body>
<div data-when-js-is-on>
JS is on.
</div>
</body>
</html>
(You'd probably have to tweak it for poor IE, but you get the idea.)
My solution
.css:
.js {
display: none;
}
.js:
$(document).ready(function() {
$(".js").css('display', 'inline');
$(".no-js").css('display', 'none');
});
.html:
<span class="js">Javascript is enabled</span>
<span class="no-js">Javascript is disabled</span>
Alex's article springs to mind here, however it's only applicable if you're using ASP.NET - it could be emulated in JavaScript however but again you'd have to use document.write();
You could set the visibility of a paragraph|div to 'hidden'.
Then in the 'onload' function, you could set the visibility to 'visible'.
Something like:
<body onload="javascript:document.getElementById(rec).style.visibility=visible">
<p style="visibility: visible" id="rec">This text to be hidden unless javascript available.</p>
There isn't a tag for that. You would need to use javascript to show the text.
Some people already suggested using JS to dynamically set CSS visible. You could also dynamically generate the text with document.getElementById(id).innerHTML = "My Content" or dynamically creating the nodes, but the CSS hack is probably the most straightforward to read.