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How to really isolate stylesheets in the Google Chrome extension?
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I'm making a browser extension. It creates some UI on the page. In the UI, there are elements which are being forcefully modified by css depending on a website is opened. Aside from making it ugly, it also might break the whole UI!
The question is how to protect my poor elements from css terror?
There are multiple options such as iframes, extremely specific classnames, and adding the !important field everywhere. But your best bet might be to use a shadow DOM which allows for a hidden DOM tree attached to the regular (perhaps that third party website) DOM.
I've seen another thread on this post that might provide more detailed answers.
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I'm building a very simple website with a few different sections like "about us", "pictures" and "contact".
I'd like to know which is more efficient (better performance and lower response time):
1.Using Javascript to manipulate the DOM and change the contents of the main section whenever the client clicks one of those item in the menu ("about us", "contact" etc) or...
2.Creating a new page (different HTML and CSS files) for each of these 4 or 5 sections I want the site to have?
Thanks in advance!
For decisions such as this is why front-end frameworks like Google Polymer, AngularJs, React, etc were created.
Obviously having a page change (as suggested in 2.) will be much slower than 1, since:
The entire page has to reload (dom is cleared, then re-constructed)
All shared styles/bindings have to be reapplied
Overhead of making duplicate requests (which introduces network latency to page load)
However, though 1 may seem like an appealing design choice, performing un-optimized dom-manipulations (via jQuery) may actually hurt performance even more, since you'd introduce a ton of thrashing, and unnecessary middle steps.
Frameworks like React, handle this by using this by simulating a virtual DOM where:
All operations are calculated in memory
Changes are then optimized
Only the diff of the changes is applied to the actual DOM
Modern web-component Frameworks (like Polymer, x-tag) handle this by using declarative html syntax to bind data to HTML/JS behavior. The optimizations work by:
Leverage shadow dom's which perform operations and styles only to the scope of that element
Statically binding all events to elements created (no need for repetitive even callbacks)
Static referencing to all Id' elements in the component
This results in O(1) selection speed vs jQuery's O(n) approach
Write once, use/customize everywhere approach
As response time and performance are your main priorities. DOM manipulation will better suit your needs by allowing you to implement smooth transitions without a full page load.
As suggested above, you might benefit from using a framework that utilises virtual DOM. In which case, as your requirements are quit simple, a small component-based UI library like riotjs might suffice.
It might also be worth having a look at a single page website with sections that can be scrolled to manually or using a top nav. This would certainly meet your two main priorities.
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How to handle JavaScript being disabled in AngularJS
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Closed 8 years ago.
I have learned angular.js, and it's awesome , i'm impressed. i want to use it in my website, but what if our some of user has disabled JavaScript on there browser, they should still gonna see my website content ?????. i'll appreciate your help.
In most cases when js is required, you should add noscript which will be displayed when js is disabled. In that tag you need to warn user that he/she should enable js.
In addition to other answer, I am quoting from Angular book:
Not everyone’s browser supports JavaScript. Let everyone see all of your content and use your app without needing to execute code in the
browser.
The world has changed since these concepts were born. Point #1 is no
longer true for any interesting population. If you’re running a
browser without JavaScript, you’re rele‐ gated to sites created in the
1990s
Or make a div with a warning/notice text (maybe in center of page), and hide that div in js (first thing in your code)
So, if the user does not have js enabled, they will see the nice warning
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I am building a prototype for a mobile section of a website. It uses no dynamic staff, just jQuery and Foundation 4. When I test the site in the iphone's browser, it's very very slow to load and to respond to touches. Can some experienced folks please tell me all things to make sure the site loads and operates faster on the mobile device?
All my images are saved "for web", so they shouldn't be a problem. Could it be slow because my CSS style sheet is very lengthy? I am not an expert at combining and applying one classes to a lot of things yet, so may be I have too many id-s and separate classes? Would that be a big deal in this case though? Also, could it be slow because I am using Foundation, jQuery and a Flexlider plug in and each of them has their own multiple style sheets and .js files? Should I throw away any files I am not using from their folders? Am I on the right track and what else can I do? Thank you in advance.
There are some things which helped me to make my mobile app more faster. I had the same issue as you, the screen response was very low.
Get rid of every unused code
I had a lot of commented code and files that i actually didn't use. This includes css styles that aren't used.
Do you even need classes or Ids?
Looking at my app, i had almost on any element a class or Id. Were i instead could use a element selector. here some more info about the selectors. Follow the DOM structure. I mostly used a class for groups and Ids for one specific element(which i almost never needed).
Check if you have css styles that doesn't add something
Sometimes you have multiple styles that doesn't actually add anything to it. A great example is using a float: *; and display: inline-block;. When using both of these on one element has no extra function as float makes the element inline-block by default.
optimize you script
With this i mean, see if you can shorter you codes with the same functionality. Using two almost identical functions? short them to one function. Also using premade function of your script language will really help you to make your code faster. So don't create your own sort function, but use the premade function.
For help on optimizing you code, i suggest you to take a look here.
jQuery selectors
Make your jQuery selectors more specific. For example:
You may have a div with class content.
<div class="content"></div>
Instead of selecting it with
$('.content')
You could use
$('div.content' )
jQuery can now restrict the search to DIV elements only.
More info fore more efficient jQuery selectors here
Store determenation code
When you get information, for example screenWidth minus the width of a other div, and you using this more then once, store it! This way your webpage hasn't to do the calculate over and over and can just get the variable.
Don't use 'big' plugins when using half of it
When you only use a small part of a plugin you're using, it's better to find or a other plugin or code it yourself. Loading the plugin files might harm your performence, would be a shame if it actually wasn't even necessary.
This is just a global view were I had a big advantage on and I hope you can find a fine use for this.
Feel free to correct me when I'm wrong.
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This is more of a general practice question that a problem specific one but I'll give an example of what I mean. There are a lot of things you can control with CSS that you can also do with Javascript, but is one better to lean on than the other?
Example:
I have four buttons in a nav that are given a class of "selected" when the section they're associated with is in view. So I could either write a CSS statement for each button (or have Sass do it for me with a mixin)
#home-butt.selected{
background-image: url(images/home-up.png);}
#about-butt.selected{
background-image: url(images/about-up.png);}
#work-butt.selected{
background-image: url(images/work-up.png);}
#contact-butt.selected{
background-image: url(images/contact-up.png);}
Orrr I could write something in javascript to do the same thing. (*I gave the images a title attribute that matched the image name so it could pull from there).
title = $(this).attr('title');
$(this).find('img').css("background-image",
"url(" + 'images/' + (title) + '-up.png' + ")");
So my question is which is better to use? Is it the javascript because it's less lines of code? Or the CSS incase javascript is disabled? Or is this a very situational question where there isn't always a right or wrong answer?
Opinions and rebuttals are welcome!
To answer your question about "is one better to lean on than the other?"
Keep in mind, that CSS has a specific purpose. To apply the look to your application. JavaScript on the otherhand, is mostly the feel of your app. Always prefer CSS over JavaScript when editing styles.
The only time that you ever should modify styles using JavaScript is when you have a dynamic application, and need to change styles based on some unknown variable. Even then, a lot can be achieved with just using CSS.
Also keep in mind that you are using jQuery. think about jQuery's constructor. it is a CSS selector.
With the concept of CSS pseudo-classes introduced, there is very little that you cannot achieve style-wise with CSS.
In many cases where Javascript developing makes what I'm trying to accomplish much more easy and other cases where CSS does that to.
" In the end each "language" has its appropriate place in web development and used wisely can enhance both development and user experience. Learn what those uses are (I recommend experience learning) and apply wisely. In my experience, set in stone rules such as "Never use JS when a CSS solution exists" (paraphrased) are rarely best in the practical world. "
If you are working with layout, use CSS, if your creating the look and feel use CSS, if your doing animations use CSS3
If you attach event handlers or reacting to user input use JavaScript.
Usually you want to use CSS, because it's much faster than javascript. Also there are going to be users with javascript disabled, which aren't going to see your enhanced presentation if it relied on js function.
The usual answer is, use CSS when you can, because it will work with JavaScript disabled, and also because you don't have to deal with issues like waiting for elements being available in the DOM before referencing them.
But sometimes it depends. Keep in mind that:
Depending on the selector or properties you're changing you may have issues with browser compatibility.
If you're changing the image like in your example, you may see it flicker while the new image is loaded. You can avoid that by using a sprite image, or preloading the images with JavaScript.
As a general rule of thumb, I would use CSS for styling and JavaScript only to "make the page alive".
So the best and the most ideal use of JavaScript is to add and remove classes from elements
- classes, which your CSS is depend on.
Loading the jQuery library to perform this simple task is unnecessary and relying on javascript to apply background images to your img tags is unnecessary as well.
If it can be done properly in CSS, and work in all browsers, then it should be done in CSS.
Javascript is for more advanced or complex tasks, which require interaction or animations that CSS can't provide for all browsers (due to cross browser compatibility issues - check out caniuse.com)
In your example, if the .selected attribute is being given dynamically by javascript for instance:
makeSelected(elm)
{
document.getElementById(elm).className='selected';
}
then i would still personally add the styling for .selected in CSS instead of adding the image through javascript.
If you're adding .selected based on the current page you're on and not through javascript then I would recommend using CSS.
I prefer CSS over Script for one main reason Browser compatibility
There are just soooo many times when one script code or the other isn't compatible in one browser or the other (cough or just IE)
With css I haven't had such issues yet (touchwood) and also if there were any issues CSS's won't affect as much as script's which just don't let any other following codes to execute.
Let me provide my opinion.
Personally I don't believe a website should have a lot of "gimmicks" in terms of designing.
BY gimmicks I mean hovering effects, music in the background(absolute no-no) or other "eye-catching details". All of this looks good the first time but subsequently visitors get fed up with this distractions.
Without deviating from the main issue. CSS/JavaScript for styling.
Well they do exist hand in hand. The best example for this would be Bootstrap library. Although I have never used it personally but it seems amazing what can be achieved using CSS and JavaScript.
So, We will need both to design spectacular website. CSS helps in the basic designing and to make the website more responsive we use JavaScript and its derivative libraries like Jquery for all the finer looking stuff
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Closed 10 years ago.
Just found out about the CSS tilde selector and it seems like it could be an elegant way to handle toggling input visibility.
The use-case I have in mind is when you only want to display an input to the user when they have checked a checkbox. Currently I do this with javascript and attach listeners to each checkbox, which then search through the DOM to find the appropriate input and toggle a class.
So the question is, why is this bad? And if it isn't, why isn't this prevalent? Why do we do this with .js rather than CSS? It seems to me they are both manipulating the presentation layer in fairly similar ways...
Bonus points for resources.
HTML is the Model, it contains the Data
CSS is the View, it contains the Styles
JS is the Controller, it contains the Interactions
This MVC structure makes for a powerful delegation of responsibility. When you want to change the state of a widget on a page, you can use JavaScript to change the available styling hooks:
jQuery used for brevity
$('#button').on('click', function () {
$('#widget').toggleClass('hidden');
});
CSS:
.hidden {
display: none;
}
Using this structure will easily allow you to change how interactions are performed. If you decide later that the widget should be animated, it's a simple change.
Using JavaScript also has the advantage of being backwards compatible. The percentage of users who have JavaScript disabled is remarkably few. While I highly recommend supporting people with JS disabled, that can often be done simply by showing all the content by default, and hiding things only for users who have JS enabled.
The use-case I have in mind is when you only want to display an input
to the user when they have checked a checkbox.
If you're planning to use the :checked selector for that, your app won't run in old browsers (IE < 9). If you're OK with this restriction, that is, only modern browsers concerned, CSS will do fine as well.
Using JS ensures that your site will run on older browsers too, provided the users have JS enabled.
You can also use a mix of both and it will ensure that your page works in modern browsers even with JS disabled as well as JS-enabled old browsers.
It is often easier to detect whether the browser has JS disabled (e.g. using a stylesheet inside <noscript>) than determining whether a browser supports certain CSS selectors.
Therefore using a JS solution allows you to easily place a disclaimer asking the user to enable JS for the page to work properly.
Though, again, if your site is not aimed at general public that may be using IE8 and below, the CSS solution will do just fine.
I would say if you can get away with using the tilde selector, or css in general, then go for it. CSS imho is a cleaner, usually more concise and superior performance way to accomplish the same thing as toggling the item in js. Plus, the browswer support for the tilde is quite good - see http://www.quirksmode.org/css/contents.html
There are times when you must use javascript to accomplish this, for example the element to hide is not a sibling or a descendant of the element in question.