This is one of those "what should we do about this"-questions. As you know, web components are supposed to be small, contained applications for websites. However, sometimes these needs to be styled depending on the site they're embedded on.
Example: "Sign up to our newsletter"-component. This component would have a few key items:
An input box
A button
Maybe recaptcha
A method that talks to your service once the button is pressed (passing in the email)
We're going to use Google and YouTube as examples. Google's color scheme is blue (let's imagine that) and YouTube's color scheme is red. The component would then be something like <newsletter-signup></newsletter-signup> on the page you're embedding it in. Both Google and YouTube have this.
The problem comes in, when the component needs to inherit the styles from Google and YouTube. A few deprecated CSS selectors would be great for this, because Google and YouTube's style sheets could simply enable colors for the Shadow DOM, so we wouldn't have to copy/paste the styles. The component should theoretically not know anything about the styles from the host, because we want it to inherit from the host (Google and YouTube).
At the moment, I'm creating a web component using Angular 6, which has a lot of styles, because it has a lot of elements. I'm copy/pasting styles, Bootstrap, icons, and so on from the host site, then styling them based on <newsletter-signup brand="google"></newsletter-signup>. So if the brand is Google, the colors should be red, for example.
This is really bad, because of a few reasons:
Styles have to be updated on both the web component and on the host
Duplicated code is never a good idea
If all the styles are copied 1:1, the amount of bytes required for styles is doubled
How would I, as a developer, take this into account? How do I make styles on the host, then apply them on my web component (call it inheritance)? I'm sure someone has had the exact same problem with Shadow DOM as I am experiencing. Thanks for reading.
I realize you do not want to write same kind of rules for your common component(selector)
i.e. you want to do styling as where your common selector is placed.
Things you can do to handle this:
1. Create your own logical css framework
Write most commonly used CSS rules in global css.For example if you have integrated bootstrap and you want to override bootstrap, you will write most common overrides in app.css which overrides bootstrap.
"styles": [
"node_modules/bootstrap/dist/css/bootstrap.min.css",
"src/styles/app.scss"
],
This app.scss should be written in way to which you can override.
Send Rules as input
send custom rules Obj and use in elements you want to override.
<newsletter [input]="customRulesObj"></newsletter>
component.ts
customRulesObj = new CustomRulesClass();
customRulesObj.color = 'red';
You can send rules in input in various component by creating a common class
as you know where you are embedding this component.
Extend this component from a common component
If you are too concerned for css you can extend your component from a common component which provides you with css logic as per need.
export class NewsLetterComponent extends CSSComponent implements OnInit
{
}
css-component.ts
In this component can logically define css as per host, current routerlink and
other multiple if else condition.
You can define rules by switch case conditions and bind those rules to component you have extended.
One of the biggest must-do's of web components is: My host (page where I'm embedding my web component) should not depend on the web component nor know about the web component.
What this basically means: Styles of my web component should not be shared with the host.
If my host decides to update the styles, it should affect my web component. Not the other way around. To solve this, I imported the external styles from my host directly inside the CSS file using #import. Here's an example:
import url("https://my-host.com/styles/core.css");
my-component {
//all styles goes here
}
I did this using SASS but can be done using regular CSS.
This is not a great solution at all, but it does what I want: Inherit the styles from the host. Although I would have to import every stylesheet there is, it still works.
A downside to my solution: When I load the page, it will send a request to the style from the <link> element inside the <head>-tag my host, but also to the style inside my import. So the styles are loaded twice. For our application, which is internal use only, it doesn't matter if we request additional ~200 KB data.
This question is a few years old and the situation has changed. The way to share styles with web components is now to use link tags to a shared stylesheet.
Inside each component:
<link rel="stylesheet" href="https://my-host.com/styles/core.css">
Reference:
https://github.com/WICG/webcomponents/issues/628
Related
The browser I'm using, qutebrowser, allows me to set a CSS file that applies those styles to every web site (but doesn't allow you to set it per page/domain, as far as I can tell), so I downloaded a dark theme CSS stylesheet from solarized-everything-css, but it seems the result on some website is unsatisfactory.
Therefore, I'd like to know if CSS offers a way to not apply a sequence of rulesets (in my case it'd be the whole stylesheet) on some domains. Something long the lines of
#this-web-site-is-NOT-in-the-black-list-in("list.txt") {
/* the content of the dark theme CSS goes here*/
}
If it was possible, then I would add each problematic site to that sort of blacklist.
CSS itself cannot do this, because CSS is designed to apply only to a site from which it is loaded within the browser environment. Normally this happens by looking at resources listed in an HTML file's <head>, but can also happen from JavaScript injection via userscripts/addons/extensions a user has installed in their web browser.
So you need to use a 'user' style for this, which means you need to use a web browser that supports this. If the browser you're using (qutebrowser) does not allow you to set specific domains/URLs, then this will not be possible for you without creating your own user script (written in JavaScript, presumably) to apply this functionality on top of what the browser supports natively.
I want to create a web component using svelte. To create a web component it's necessary to include the svelte tag option
<svelte:options tag="{"my-custom-component}"></svelte:options>
It creates a custom component with that name but doesn't work properly because we have to provide this tag for all the child components as well! I added it to all the child components but it still doesn't work, turns out I use third-party libraries and I don't know any way to have that option there!
Is there a way to create the custom components with svelte which includes third-party libraries?
You can use regular svelte components (including third party) ones inside your component.
But you'll need to compile those with different compiler settings in your rollup/webpack config.
And due to the nature of scoped styling in web components (Shadow DOM) the css won't work in these components. So it depends on the library if it still works.
You might be able to turn off scoped styling in the future:
Issue #1748: Custom element without shadow DOM
But scoped styling could have been the reason why you wanted/needed webcomponents in the first place.
For an organization I work for, there is a common stylesheet that all web applications are supposed to use.
For example, they expect some elements to be in thead.table-sortable th.table-sortable-sorted-down a:after to add a sorting icon. Now, in an Angular application, I use a component library (primeng) that has a simple element that just has the class .pi-sort-up for the same thing.
How can I map / copy /use part of the organization css into my application's css, to just copy the interesting stuff without requiring the complicated nesting on component (which I have no real control on anyway)?
We could use css, sass, or even dynamically generate css rules in javascript. I'd prefer avoiding changing the DOM at runtime for all matching components, as it could be quite dynamic.
EDIT: A build-time solution (e.g. with sass) isn't the preferred way, but could be acceptable if nothing else.
If the company style sheet is readonly for you, there is not much you can do at all. You will have to load the whole document wherever you need some parts of it. A possible "workaround" to avoid that would be to write a backend program (in PHP or node.js) which opens the company style document and looks only for a specific CSS rule which it then copies and pastes to some other style document.
However, this approach would be very dynamic as well and you needed to execute the backend script with each request, for the original company style sheet could change always... If your company could agree, you should use a preprocessor like SASS or LESS and define a structure for the company style, dividing it into several documents that can be loaded on purpose.
I'm a web developer, not an CSS expert. We recently started using Angular and I'm wondering what is the best practice applying styles in Angular templates.
Discussion we have at work is whether to use external CSS files or internal style tags. We do not have too many templates and each template mostly has its own unique styles. We are debating between external CSS files and/or internal styles.
Couls someone provide an expert opinion on this subject.
Internal styles are only applicable to the page that includes them. As such, if you want to update common styling (such as a menu) on multiple pages, you'll need to update each page individually.
Considering you'll almost definitely have certain styles apply to elements on more common to more than than one page, you'll definitely want to opt for external stylesheets. This allows pages A and B to both inherit styles from a single style.css or similar file.
This way, you can load all the relevant styles with a single line of code in the <head> of each page:
<link href="style.css" rel="stylesheet">
And you only have to update style.css when you want to update multiple page's styling.
Angular brings scoped CSS from v1.5 up (when components were introduced - I believe). It's a good concept but, in small to medium apps, the difference is hardly noticeable. You should only consider using scoped CSS in conjunction with a tool that knows how to make the best of it (i.e. Webpack).
If you're not using Webpack, just stick to the classic model: one big style-sheet.
Note that technically, regardless of stack, if you want to provide the best possible experience (fastest loading times without FOUC) you want to put all the above-the-fold and general layout-ing styles inline, preferably in a head <style> tag and everything else inside a stylesheet loaded asynchronously.
Read this article about loading CSS async.
I'm writing a Chrome extension that injects HTML into a displayed page. I want the injected HTML to have it's own style, protected from the CSS that may be present in the host page.
I've tried using conventional CSS, and still suffer from style corruption from the host page.
After watching the Polymer presentation from I/O 15, I was wondering if there are any new, Chrome-specific techniques that I can use to achieve this?
What you will want to look into is shadow-dom. This will enable you to create a widget/component (which would be your injected html). This would mean that the DOM tree for the widget/component is encapsulated and no external styles from the page will affect it. There is a good article on html5rocks covering this. You may also want to look into WebComponents. Bear in mind that this functionality is only available in the latest browser versions.
Two things that I currently use at my place of work are:
css-modules
react-css-modules
I use react at work, hence react-css-modules, but css-modules should work in your case. It's not Chrome specific, but we use them within the context of each component we build. Basically, like the docs state, a class of row would become something like table__row___2w27N. The breakdown of the built name is the filename of the CSS than the class name followed by a base64 hash of 5 char. I hope this helps.
One potential downside is Webpack would be required.
Here is an example of our component folder structure:
- component
- Component.jsx/js
- component.css/scss/sass
- component.test.js