I'm using react with sass.
It's look like both have same benefits.
Locally scoped, No more conflict etc. What is the main diffrence between
style.scss
vs
style.module.scss
Why do we need .module prefix?
Short Answer
*.scss is normal SCSS file while *.module.scss is SCSS file with CSS modules.
According to the repo, CSS modules are:
CSS files in which all class names and animation names are scoped locally by default.
This solves the problem of typing ultra specific CSS class names to avoid clashes. Good bye .phone-page-contact-form-edit-card-default-button-blah-blah and hello .default-button
Usage
Below is the usage for *.scss
.ultra-specific-class-name_item {
display: flex;
}
If you use SCSS in a normal way, you must declare the class name as a string
// Simply import
import './foo.scss';
const App = () => (
<div className="ultra-specific-class-name_item">
foo bar
</div>
)
Below is the usage for *.module.scss
// No need of any ultra specific classnames
.item {
display: flex;
}
If you use SCSS as a CSS module, you must use them as how you would use a JS module.
// import as a js module
import styles from './foo.module.scss';
const App = () => (
<div className={styles.item}>
foo bar
</div>
)
Output
<!-- Normal SCSS -->
<!-- it will not be transformed -->
<div class="ultra-specific-class-name_item">foo bar</div>
<!-- SCSS with Class Module -->
<!-- hash values are suffixed to the class name -->
<div class="item-35ada5">foo bar</div>
<!-- newer versions will even prefix the file name
to the class name -->
<div class="foo__item-35ada5">foo bar</div>
Related
I was looking in for a way to dynamically generate a stylesheet for specific parts of a component that already rely on css for specific things. I was wondering how I could create styles that use compound selectors without dynamically depending on the state of the component (the number of children to render for ex).
I found that material-ui and other libs uses this make-styles or styled-components.
Are there any simpler/hacky implementations of that same principle?
Thanks
You can use CSS modules in React for component specific styles.
Make a css file and name it *.module.css
Example:
firstComponent.module.css
.container {
display: flex;
}
.firstChild {
flex: 1;
}
In your .tsx or .jsx file:
import style from './firstComponent.module.css';
const FirstComponent = () => {
return (
<div className={style.container}>
<div className={style.firstChild}>First child</div>
</div
)
}
I have two .jsx files that represent their respective components.
The first one is, Blog.jsx
import React from "react";
import '../assets/css/blog.css';
export const Blog = () => (
<div>
<h1>Hello Blog</h1>
</div>
)
With its respective CSS file, blog.css
div { background: #ff481f; }
and the second one is, Landing.jsx
import React from "react";
import '../assets/css/landing.css'
export const Landing = () => (
<div>
<h1>Hello Landing</h1>
</div>
)
With its respective CSS file, landing.css
div { background: #86ff2b; }
I have added routing and called instances of those two components on the App.js file which is the default file of a React application. After running the application, when navigated to components, I faced a problem that the background color is the same for both of the components (It loads landing.css only and never changes).
How can I fix that problem that each component only uses its respective .css file and loads it?
By default webpack and other build tools will compile all CSS files into one, even if css was imported in separate JSX files. So you can't use different CSS files and expect you don't affect on another part of page.
You have some options:
Use BEM for naming class names.
Use cssModules. In this case elements will have their own css class name and styles will not affect any other elements except if you use :global selector.
css-module
Using html tags as css selectors is a bad practice (because there is the behaviour you describe).
You should use only css classes or inline styles (using id's is another bad practise, id's have high priority).
div {
width: 20px;
height: 20px;
}
#id {
background: red;
}
.class {
background: green;
}
<div id="id" class="class"></div>
In case using css classes there is the same problem (when you have two similar classes). And this case is decided using css modules (set of rules of building) or you can use css-in-js (external library) which has its pros and cons. Also you can use BEM (methodology) and if your application is not big you can avoid this trouble.
css modules will add to your classes random hash and instead .my-awesome-class-name you will get .my-awesome-class-name-dew3sadf32s.
So, if you have two classes .class in the first file and .class in the second file in the end you will get two classes .class-dew23s2 and .class-dg22sf and you styles will resolve as expected.
css-in-js is a similar way except you should write your styles using javascript with some profits like including only those styles that are needed at the moment (what you are looking for right now) and several others.
You can code using pure css / scss / postcss / etc but many companies already choose between css modules and css-in-js.
BEM is just naming conventions for your class names.
And lastly - if you use inline-styles using react you should remember:
{} is constructor of object and {} returns new object on every call, it's mean if you write something like:
class MyAwesomeComponent extends Component {
render() {
return <div style={{color: "red"}}></div>;
}
}
or
class MyAwesomeComponent extends Component {
render() {
const divStyles = {color: "red"};
return <div style={divStyles}></div>;
}
}
div will re-render every time your render will call because div takes new prop.
Instead, you should define your styles (for example) in outside of your class:
const divStyles = {color: "red"};
class MyAwesomeComponent extends Component {
render() {
return <div style={divStyles}></div>;
}
}
Don't define your css using HTML tags because it will affect your entire application.
use className,id or inline styling.
like- App.css
.myApp{ color: red;}
#myApp2{ color: blue;}
App.js
import './App.css'
<div className="myApp">color changed by className</div>
<div id="myApp2">color changed by id</div>
<div style={{color:'red'}}>color changed by inline object styling</div> // inline styling
This is not the best solution if you are looking forward to improve yours css imports/loads.
However could be the best solution if you dont want to go in deep in css, resolve the problem fast and keep working with HTML tag.
You can add a div for each component, define an Id for the div and wrap the component. Afterwards in the component's css fies you are going to define all the styles starting with the #id so all the css classe or HTML tag will affect just the corresponding component.
//App render in root
ReactDOM.render(
<App />,
document.getElementById('root')
);
//App
function App(props){
return [
<Blog />, <OtherComponent />
]
}
//Blog component
function Blog(props){
return <div id="blog">
<h1>I am Blog</h1>
</div>
}
//Other component
function OtherComponent(props){
return <div id="otherComponent">
<h1>Im am other component</h1>
</div>
}
/* blog.css*/
#blog h1{
color:yellow;
}
/* otherComponent.css*/
#otherComponent h1{
color:green;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<div id="root"></div>
Font Awesome is not working in my shadow DOM since I have the following in it to prevent styles from leaking in and out:
:host {
all: initial; /* 1st rule so subsequent properties are reset. */
display: block;
contain: content; /* Boom. CSS containment FTW. */
}
I'm able to use other stylesheets by just inlining them within the :host property, but that doesn't work with Font Awesome since it uses relative paths in its stylesheet.
I found this post and tried it with the scoped CSS I implement, but the icons show as squares, as can be seen in my example.
I had the same issue with StencilJS.
After hours of struggle and the answer from #Intervalia I was able to fix it.
The problem is that the browser doesn't load the font files when they are only included in the shadow dom (your custom web component). This means that the fonts also has to be included in the normal html file (aka light DOM) so that the browser can detect and load them in order to make them available in the shadow dom.
In my case I didn't use Font awesome instead it was a custom font but I tried it a second time with font awesome and a clean Stenciljs project. The solution is always the same doesn't matter which custom font you need.
Step 1: Move the font into your project. I created a seperate "assets" folder inside the "src" folder to have access from all the components. In this example I downloaded font awesome for web environment https://fontawesome.com/download. (I wouldn't recommend "npm install" since you have to use it in the index.html too)
Step 2: Prepare your web component (in this case my-component.tsx). You can import multiple css files using the styleUrls property. Just import the fontawesome css from your assets directory.
import { Component, Prop, h } from '#stencil/core';
#Component({
tag: 'my-component',
styleUrls: [
'my-component.css',
'../../assets/fontawesome/css/all.css'
],
shadow: true
})
export class MyComponent {
#Prop() first: string;
render() {
return <div> <i class="fas fa-question-circle"></i> </div>;
}
}
Step 3 prepare the file where you want to use the component (in this case index.html). The important line is the "link" tag. This includes the "font awesome css" again and force the Browser to really download the fonts.
<!DOCTYPE html>
<html dir="ltr" lang="en">
<head>
<meta charset="utf-8">
<title>Stencil Component Starter</title>
<link rel="stylesheet" type="text/css" href="./assets/fontawesome/css/all.css">
</head>
<body>
<my-component first="Stencil" last="'Don't call me a framework' JS"></my-component>
</body>
</html>
I know it feels wrong and looks weird but it is not enough to include font awesome only in the index html or in the web component. It must really be included in both files. That doesn't mean the Browser will load it multiple times - it will only be loaded once.
That means that you can't deliver the font with the web component - as far as i know. This isn't a stenciljs bug this is a general problem of the browsers. Please let me know if you have better solutions.
Just for fun here is a screenshot that shows that the browser doesn't load the fonts when it is only included in one file. http://prntscr.com/p2f9tc
Update 05.10.2019:
If you want to use your font inside your web-component the explanation above is correct and still necessary. But you can also use the slot tag inside the web-component. Than you automatically bypass the font from outside (the html) into the web-component. But notice it only works for the stuff you write between the tags of your web component.
That means you can use <my-component> <i class="your-font"/> </my-component>. In this case you don't have to import the font into the web components.
One thing I have noticed is that if the page does not load the CSS file then the shadowDOM won't load it either.
I really think that the only problem us that if the font is not defined on the page that it will not work in the component since the rest of the CSS seems to properly apply to the shadowDOM elements.
This example shows just the shadowDOM trying to load the CSS and it does not work:
let template = `
<style>
:host {
display: block;
}
</style>
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.7.1/css/all.css" integrity="sha384-fnmOCqbTlWIlj8LyTjo7mOUStjsKC4pOpQbqyi7RrhN7udi9RwhKkMHpvLbHG9Sr" crossorigin="anonymous">
<header>
<h1>DreamLine</h1>
<nav>
<ul>
<li>Tour</li>
<li>Blog</li>
<li>Contact</li>
<li>Error</li>
<li><i class="fa fa-search"></i> Search</li>
</ul>
</nav>
</header>
`;
class MyEl extends HTMLElement {
connectedCallback() {
this.attachShadow({mode: 'open'}).innerHTML = template;
}
}
customElements.define("blog-header", MyEl);
<i class="fa fa-battery-full" style="font-size: 45px;"></i>
<hr/>
<blog-header></blog-header>
<hr/>
And this example shows both the page and the shadowDOM loading it and it works:
let template = `
<style>
:host {
display: block;
}
</style>
<header>
<h1>DreamLine</h1>
<nav>
<ul>
<li>Tour</li>
<li>Blog</li>
<li>Contact</li>
<li>Error</li>
<li><i class="fa fa-search"></i> Search</li>
</ul>
</nav>
</header>
`;
class MyEl extends HTMLElement {
connectedCallback() {
const styles = document.querySelector('link[href*="fontawesome"]');
this.attachShadow({mode: 'open'}).innerHTML = template;
if (styles) {
this.shadowRoot.appendChild(styles.cloneNode());
}
}
}
customElements.define("blog-header", MyEl);
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.7.1/css/all.css" integrity="sha384-fnmOCqbTlWIlj8LyTjo7mOUStjsKC4pOpQbqyi7RrhN7udi9RwhKkMHpvLbHG9Sr" crossorigin="anonymous">
<i class="fa fa-battery-full" style="font-size: 45px;"></i>
<hr/>
<blog-header></blog-header>
<hr/>
The code I like to use looks for the <link> tag I want in the body and then uses a clone of that tag inside the shadowDOM. This way my component is not out of sync. Yes, this can cause problems if the component was not expecting a change in the CSS but I find it works well for my projects.
If you don't need shadow: true then you can load the all.min.css directly via the index.html or the main application. Even loading the all.min.js file works.
If you need it within the shadow dom, then you need to load the all.min.css in index.html and also load it within shadow root using something like this.
`
componentDidLoad(): void {
this.hostElement.shadowRoot
.getElementById("some_Id")
.insertAdjacentHTML(
"afterbegin",
`<link rel="stylesheet" href="${getAssetPath(
"/fontAssets/fontawesome-free/css/all.min.css"
)}" />`
);
}
`
I wanted to share what I did for loading in Font Awesome icons to my stencil components (shadow enabled)...
After several hours into researching this topic, I think I've discovered a solution that will be the most efficient for my components to be bundled in a agnostic way and free of any additional style sheet includes in the HTML header.
My solution was to use the stencil-inline-svg module and then import the svg file directly from the Font Awesome module like this:
// the reference to the svg can be anything (searchIcon name).
// just make sure to import the correct svg from fontawesome node modules.
import searchIcon from 'fontawesome/svgs/regular/search.svg';
#Component({
tag: 'search-icon',
styleUrl: 'search-icon.scss',
shadow: true,
})
export class SearchIconComponent {
render(){
return (
{/* Not ideal to use innerHTML but this renders the full SVG markup */}
<span class="search-btn" innerHTML={searchIcon}></span>
)
}
}
Now, I can set css rules to modify the color and size of my icon like this
.search-btn {
width: 40px; // Set SVG size at the parent.
svg path {
fill: #fff; // Update svg path color.
}
}
Obviously this requires a little bit of Font Awesome icon knowledge so you know which icons to import.
Shadow Doms's style is scoped. And it does not interfere with outer style
FWIW I created a helper method to create a link for font-awesome at the parent page level. Not sure if this is in violation of any custom-elements/Web Components standards but I'll go ahead and post here in hopes that I'll be corrected :) It works for my use case w/ internal web applications for now though.
export const addFontAwesomeStyles = () => {
injectStylesheet("https://use.fontawesome.com/releases/v5.13.0/css/all.css");
injectStylesheet("https://use.fontawesome.com/releases/v5.13.0/css/v4-shims.css");
}
export const injectStylesheet = (href: string) => {
const links = document.head.querySelectorAll("link");
// Already been injected
for(let l in links)
if(links[l].href == href) return;
const link = document.createElement('link');
link.rel = "stylesheet";
link.href = href;
document.head.appendChild(link)
}
Then in your StencilJS component's construtor you can use it like so:
//...
constructor() {
addFontAwesomeStyles();
}
I have header.js file like this:
import React, {Component} from 'react';
import Classes from '../css/style.css';
class Header extends Component {
render() {
return (
<header>
<div className={Classes.logo}>Logo</div>
</header>
)
}
}
export default Header;
the problem the class name logo is not loaded, after inspect this in the browser the html appear like this:
<div>Logo</div>
why is that ?
I haven't seen CSS classes used this way in React before. Does this this work?
return (
<header>
<div className="logo">Logo</div>
</header>
)
This assumes you have a .logo class in your style.css and your bundler is configured to handle CSS.
Using {Classes.logo} would imply you have some stateful object named Classes with a logo property
All you have is imported a CSS file, which has no dynamic state, therefore you only need a string of the classes to load on this tag
className="logo"
Where the CSS has
.logo {}
I have several components which have the following CSS/component structure
About/style.css
.AboutContainer {
# Some style
}
p > code {
# Some style
}
And I import the CSS in the componet as follows
About/index.js
import './style.css';
export default class About extends Component {
render() {
# Return some component
}
}
However, the CSS is imported in the <header> section and stays global-scope.
I was expecting CSS to be:
Component-scoped in a way that the style is only applied to things that are only rendered within this component.
Style for this component would disappear if the component is unmounted.
However, when inspecting from the browser, the styles are specified at the <header> section and gets applied to all the components
<header>
// Stuff
<style type="text/css">style for component About</style>
<style type="text/css">style for component B</style>
<style type="text/css">style for component C</style>
// Stuff
</header>
How do I import CSS to be component-scoped? It seems like I'm understanding CSS import in React ES6 incorrectly.
I was following this tutorial
Edit
Answer by Brett is correct. However, my problem turns out to be somewhere else. I created my app using create-react-app which basically simplifies setups required to do React. It include WebPack, Babel and other things to get started. The default WebPack config that it uses did not set module option for the css-loader so it defaulted to false, and as a result the local-scoping was not enabled.
Just for additional info, it seems like create-react-app does not have straightforward way to customize WebPack config, but there seem to be numerous how-to workarounds on the web.
It sounds like CSS Modules, or many of the other CSS-in-JS packages, does what you want. Others include Emotion (my current favorite), Styled Components, or many of the packages here.
A CSS Module is a CSS file in which all class names and animation names are scoped locally by default. All URLs (url(...)) and #imports are in module request format (./xxx and ../xxx means relative, xxx and xxx/yyy means in modules folder, i. e. in node_modules).
Here's a quick example:
Let's say we have a React component like:
import React from 'react';
import styles from './styles/button.css';
class Button extends React.Component {
render() {
return (
<button className={styles.button}>
Click Me
</button>
);
}
}
export default Button;
and some CSS in ./styles/button.css of:
.button {
border-radius: 3px;
background-color: green;
color: white;
}
After CSS Modules performs it's magic the generated CSS will be something like:
.button_3GjDE {
border-radius: 3px;
background-color: green;
color: white;
}
where the _3DjDE is a randomly generated hash - giving the CSS class a unique name.
An Alternative
A simpler alternative would be to avoid using generic selectors (like p, code, etc) and adopt a class-based naming convention for components and elements. Even a convention like BEM would help in preventing the conflicts you're encountering.
Applying this to your example, you might go with:
.aboutContainer {
# Some style
}
.aboutContainer__code {
# Some style
}
Essentially all elements you need to style would receive a unique classname.
Maybe react-scoped-css will help. Btw, I'm the author of this lib, if you find anything broken or simply want to improve it, you can always raise an issue or send a pr.
Because you mentioned you used create-react-app, the solution here is quite easy change just style.css to style.module.css, it will look like this:
import styles from "./style.module.css"
<button className={styles.button}>blabla</button>
More info on this article:
https://blog.bitsrc.io/how-to-use-sass-and-css-modules-with-create-react-app-83fa8b805e5e
You can use SASS (.scss) to imitate scoped CSS.
Say you need to use bootstrap in only one component (to avoid conflicts). Wrap the component in <div className='use-bootstrap'> and then created a .scss file like so:
.use-bootstrap {
// Paste bootstrap.min.css here
}
Use this file naming convention [name].module.css
and see documentation: https://create-react-app.dev/docs/adding-a-sass-stylesheet
JSX File
import React from 'react';
import styles from './index.module.scss';
const MyPage = () => {
return (
<div className={styles}>
<h1>My Page</h1>
</div>
);
};
export default MyPage;
Styles File
h1 {
color: #f3f3f3;
font-family: "Cambria";
font-weight: normal;
font-size: 2rem;
}
For me, the simple solution (without using: Css-modules or css-in-js) is to add a suffix to your class selectors like this:
className="btn__suffix"
if your component is named: FileUpload.tsx so your __suffix would be __fu, i took the first character of each word (here: File and Upload).
the end result would be:
import './style.css';
export default class About extends Component {
render() {
Return (
<div className="container__fu">
...
</div>
)
}
}
And in the Css part, your file would be:
.container__fu {
...
}
I created a rollup plugin to have scoped scss/css within a vite react project with regular import, you can check it out if it can solve your issue!
https://www.npmjs.com/package/rollup-plugin-react-scoped-css