CSS Specificity with CSS Module - css

First, let me say I understand that I have a custom component "Card" that I use in one of my routes, "Home".
Card.js
import s from 'Card.css';
class Card {
...
render(){
return (<div className={cx(className, s.card)}>
{this.props.children}
</div>);
}
}
Card.css
.card {
display: block;
}
Home.js
<Card className={s.testCard}>
...
</Card>
Home.css
.testCard { display: none; }
A problem I faced here, is that the card remained visible even though I set the display to none, because of seemingly random CSS ordering in the browser. This ordering did not change even if Javascript was disabled.
To get .testCard to correctly load after .card, I used "composes:":
Home.css
.testCard {
composes: card from 'components/Card.css';
display: none;
}
Apparently this causes css-loader to recognize that .testCard should load after .card. Except, if I disable Javascript, the page reverts back to the old behavior: the .card is loaded after .testCard and it becomes visible again.
What is the recommended way to get our page to prioritize .testCard over card that behaves consistently with or without Javascript enabled?

As I'm using CSS modules, charlietfl solution wouldn't really work as is. .card is automatically mangled to a name like .Card-card-l2hne by the css-loader, so referencing it from a different component wouldn't work. If I import it into the CSS file of Home.css, that also doesn't work, because it creates a new class with a name like .Home-card-lnfq, instead of referring to .Card-card-l2hna.
I don't really think there's a great way to fix this so I've resorted to being more specific using a parent class instead.
As an example, Home.js:
import s from 'Home.css';
import Card from './components/Card';
class Home {
...
render(){
return (
<div className={s.root}>
<Card className={s.testCard}>Hi</Card>
</div>
);
}
}
Home.css
.root {
margin: 10px;
}
.root > .testCard {
display: none;
}
This way, we don't need to know what class names component Card is using internally, especially since in cases like CSS Modules or styled components, the class name is some unique generated name.
I don't think I would have come to this solution if it wasn't for charlieftl's solution, so thank you very much for that.

Just make the testCard rule more specific by combining classes
.card {display: block;}
.card.testCard { display: none; }

Related

NextJS: Modify third-party component CSS in different pages

With third-party components, the way to include their styles is by importing their stylesheet into _app.tsx or importing the stylesheet into your component that uses the third-party component, as described here: https://nextjs.org/docs/basic-features/built-in-css-support#import-styles-from-node_modules or by adding to next.config.js like so:
// next.config.js
const withTM = require("next-transpile-modules")([
"#fullcalendar/common",
"#fullcalendar/daygrid",
"#fullcalendar/timegrid",
"#fullcalendar/interaction",
"#fullcalendar/react",
"#fullcalendar/list",
To modify the third-party stylesheet, you need to create your own stylesheet and add it to _app.tsx; those modifications might look like this:
// styles/modified-fullcalendar.scss
.fc-col-header {
width: 100% !important;
}
Another option, at least for my use case (Full Calendar) is to use CSS variables as described here in technique 2 on this page: https://fullcalendar.io/docs/css-customization. There was a lengthy thread about this on the Full Calendar issues page, as seen here: https://github.com/fullcalendar/fullcalendar/issues/5393
The problem with all of these methods of customization is that they're global, and so anywhere you use this third-party component it'll look the same. However, in my case, I want to use the component on two different pages, with different styling modifications. With most frameworks, I would simply import the relevant modified stylesheet wherever I needed it, but NextJS doesn't allow that. How can I achieve the modifications I want?
The solution is to wrap the component in a div with a specific class name, then do the css overrides in a nested format for each use case in the override file.
Explanation:
Say your third-party component is FullCalendar. It's being imported and used in the files Foo.tsx and Bar.tsx. In Foo, let's say you want the calendar cells to be green.
To make the modification, you create the file modified-fc.scss and do the following:
// modified-fc.scss
.fc-cell {
background: green !important;
}
You then import modified-fc.scss into _app.tsx in order to apply the styles globally, and you're done. However, this prevents you from changing the cell color to orange in Bar. To circumvent this, just wrap the component:
// Foo.tsx
<div className=".wrapper1">
<FullCalendar/>
</div>
// Bar.tsx
<div className=".wrapper2">
<FullCalendar/>
</div>
and then nest the classes:
// modified-fc.scss
.wrapper1 {
.fc-cell {
background: green !important;
}
}
.wrapper2 {
.fc-cell {
background: orange !important;
}
}
OR
.wrapper1 > .fc-cell {
background: green !important;
}
.wrapper2 > .fc-cell {
background: orange !important;
}

Styling from separate CSS files not applied with new components

I have been trying to build a small project with React for the past few days and all went great until today. For some reason, no CSS is applied to new components! All the CSS that worked before is still up and running but if I'd add something like a div in between an already existing div, the new div will not pick up any CSS!
Example:
<div className="DivStyle"> // Styling applied!
<div className="DivStyle"> </div> // Styling completely ignored!
<div>
It is probably worth mentioning that I am still able to style the components inline.
Also, looking at the sources in Chrome, the styles are uploaded!
Here is my concrete example:
import '../styles/drawers.css';
class BottomFilterDrawer extends React.Component<IBottomFilterDrawerProps, IBottomFilterDrawerState> {
...
public render() {
return(
<Drawer
open={this.state.isOpen}
anchor="bottom"
// tslint:disable-next-line jsx-no-lambda
onClose={() => this.toggleDrawer(false)}>
<div className="BottomDrawerContainer" style={{margin: "10px"}}> // Styling for "BottomDrawerContainer" class not applied!
...
</div>
</Drawer>
);
}
}
The CSS file:
#BottomDrawerContainer {
margin: 10px;
}
I am certain that the import path is correct, Typescript wouldn't even let me run it if it weren't.
You are applying css for class not for id. So your css must be like below.
.BottomDrawerContainer {
margin: 10px;
}
if you want to apply for inner div.
.DivStyle .DivStyle {
//style for inner div
}
do not use again same id, React create error and if show any error first you solve error otherwise browser not show anything

Applying CSS stylesheet only to active component

I'm working on a ReactJS app that has a header at the top, a menu on the left, and the "frame" in the middle is where routes and their corresponding components are loaded. I want to be able to apply a CSS stylesheet to specific components only when they are loaded. I also don't want them applied all the time or to the top header or left menu.
My expectation was that adding import 'custom.css'; to a specific component would only apply the stylesheet's styles to that component and it's children when the route is active. Instead, it applies it to the entire page even when the route/component are not loaded.
I understand that an alternative approach is styled components, but, for my use-case, a design company is supplying a stylesheet (which should remain unchanged) that we need to consume only for the sub-module I'm working on and I don't want its styles to affect the rest of the app.
How can I have a stylesheet only applied to my active route/component?
Use simple CSS technique. Suppose you have two components with different css files (say about.css and contact.css). Now consider your both CSS file have one common class with different style properties, like:
about.css
.container{
max-width: 400px;
}
contact.css
.container{
max-width: 500px;
}
Yes in ReactJS both the CSS files will load at the same time and will override any one of the style. so to solve this problem add class to differentiate this styles, like:
about.css
.about-component.container{
max-width: 400px;
}
contact.css
.contact-component.container{
max-width: 500px;
}
If you want apply only when the component is mounted, you can use the lifecycle.
The follow example is based in the idea you are using sass, React, sass-node and have the loaders into webpack.
<pre>
import React from 'react';
import './styles.scss';
class MyComponent {
constructor(props) {
super(props);
this.state = { className: '' }
}
componentDidMount() {
this.setState({
className: 'myOwnClass'
});
}
render(){
return (
<div className={this.state.className}>This is a example</div>
);
}
}
export default myComponent;
</pre>
To be able to only call that specific CSS when you need it you can use CSS Modules. You may need to update your version of react.
When saving your CSS file save it with a ".module.css" eg. "styles.module.css". The CSS in these files can only be used and accessed by hte components where are they are imported. As stated in a tutorial from W3Schools.
Let's say this is your CSS code in styles.module.css:
.container {
color: white;
}
.cont-child {
background-color: red;
}
Then in your JS file you can import the CSS file like this if the JS and CSS files are in the same directory. Make sure you point to the correct path.
import styles from './styles.module.css'
Then in your HTML section you can use it like this:
class Home extends React.Component {
render() {
return(
<main className={ styles.container } >
<div className={ styles["cont-child"]} >
Some div text about something...
</div>
</main>
);
}
}
I currently use both ways to access the selectors, since the styles variable acts like an object. I placed both of them here because the second option is capable of fetching selectors named like "btn-active". Which comes in handy in some situations. Camelcasing is considered cleaner though.
Please note: I originally posted this answer as a reply to a similar question here React CSS - how to apply CSS to specific pages only
I want to be able to apply a CSS stylesheet to specific components
only when they are loaded.
Why not apply the styles inline via React.js?
Step 1. Create the style object for the component:
var componentOneStyle = {
color: 'white',
backgroundColor: 'red'
};
Step 2. Populate the component's style attribute with the style object:
ReactDOM.render(<div style={componentOneStyle}>This is Component One</div>, mountNode);

CSS Modules & ReactJS: Parent and child CSS classes in different components

So I am building a react application and have a quick question. If I have two separate components:
and
with CSS classes navigation.css and navigationLogo.css respectively. In navigation.css I have a class named .main and in navigationLogo.css I want to have a class like so:
.main .main_in_logo {
color: red;
}
But with CSS Modules I am unable to do this, any ideas on a work around?
I just feel that the explanations here are not complete enough. In css you do .parentSelector .childSelector in order to select the child. The same rule is for css modules, but in your html/jsx you should add to the parent and the child the relevant className -> styles.parentSelector , styles.childSelector.
<div className={styles.container}>text</div>
This way you can have in your css something like:
.banner .container{
background-color:reb;
}
.banner .container{
background-color:blue;
}
Sometimes you use libraries and you want to change something somewhere down the DOM inside the library and you can't change its source code. In this case you can use the :global like this:
.parentElement :global(div)
.parentElement :global(#some-lib-element-selector)
I was looking for the same problem and didn't find the solution here, maybe because the post is 3 years old. The accepted answer is, in my opinion but not mine only, not scalable.
I don't really know if this is something new, but I found out what I would do in vanilla CSS adapted to CSS modules.
Here is what I did and fully suits my needs:
/* parent.css */
.main {
...some CSS...
}
/* logo.css */
#value main from "./parent.css";
.logo {
...some CSS...
}
.main .logo {
color: red
}
Here, we are using #value, which is a CSS modules variable and allows us to bind with another file to build a selector including the final name of the parent "main".
As strange as it looks to me, it took some time to find out about this solution, I hope this will save some time and help other people!
Why you need to create .main .main_in_logo - the main idea of styles with parent elements its not to broke your css with other styles in the future. But its impossible with css modules, because your styles will be unique forever.
But even you really need it you can use global css for these 2 components - documentation about global css for react-css-modules.
The child component should not have a css rule that is dependent upon the parent css classname.
the child should just be:
.main_in_logo { color: red; }
If you need to define styles that involve both parent and child, then the easiest way is to define the styles completely in the parent:
/* navigation.css */
.main .main_in_logo {
color: red;
}
Then have the parent pass the css class to the child and tell the child to use it:
// Navigation.js
<NavigationLogo className={navigationCss.main_in_logo} />
// NavigationLogo.js
<div className={"foo " + this.props.className}>stuff</div>
You don't need to be specify which child class you are referring to when using CSS modules in ReactjS.
so doing:
.main_in_logo {
color: red;
}
will be enough in the stylesheet.
I ended up using CSS the normal way but with BEM convention.
I mean after all, what the CSS modules do is adding the [this_name].module.css to your css classes anyway. If you typed it correctly in the first place, there's no need of using this. It's just a new abstract that allow newbies so they can just do stuff without having to worry about class names clashing.
// Main.jsx
import './Main.css'
import Logo from './Logo.jsx'
const Main = () => {
return (
<div className="main">
<Logo className="main__logo" />
</div>
)
}
/* Main.css */
.main {/* do magic */}
.main__logo {/* do magic but for Logo component */}
So maybe you had Logo component like this..
// Logo.jsx
import './Logo.css'
const Logo = () => {
return (
<div className="logo">
<img className="logo__img" />
</div>
)
}
/* Logo.css */
.logo {/* do magic for logo */}
.logo__img {/* do magic for logo's image */}
This feels much more natural.

Component is briefly rendering without styles on first render

When I open my react app, the component below flashes with width:100%, probably because it inherits it from the material-ui card.
In my react app there are a lot of these components being rendered, each with their own width which are based on the parent component's data. I set the width with an inline style based on the props.
As I understand, the component has the inline style as it is created and there should be no delay to apply it. However I see all the SceneThumb components with 100% width for a a fraction of a second, before they apply the given inline style.
If I change the css of scene-thumb-parent to include some width, say 10% for example, then I'll see them all with 10% for a fraction of a second, before the inline style is applied. That makes me think there is a delay in applying inline css, but it really puzzles me..
Is this to be expected of react? Or of html in general? Is there any way to reduce this inline style application delay? Maybe it's something to do with the dev hot reloading setup I get from create-react-app?
SceneThumb.js (code that is irrelevant to the question has been omitted):
import React, { Component } from 'react';
import './scene-thumb.css';
import Card from 'material-ui/Card';
class SceneThumb extends Component {
render() {
return (
<div
className='scene-thumb-parent'
style={{width:this.props.width, left:this.props.left}}
>
<Card
className={this.props.selected?'scene-thumb-selected':'scene-thumb'}
>
<span>
Hello world!
</span>
</Card>
</div>
);
}
}
export default SceneThumb;
scene-thumb.css:
.scene-thumb-parent {
position:relative;
text-overflow:clip;
white-space:nowrap;
overflow:hidden;
min-width: 12px;
}
.scene-thumb-selected {
border: 2px solid red;
border-radius: 5px;
}
.scene-thumb,.scene-thumb-selected {
padding: 2px;
margin:2px;
position:relative;
}
The width prop is initially null or some other value. A moment later, the prop is updated which triggers another render. This is why you're seeing the flash you're talking about.
You can test this by adding the following to your render() function:
console.log(this.props.width)
You'll probably see it logging at least twice with different values.
There are many ways you can fix this. What makes most sense would depend on the rest of the application, and your personal preference. Regardless, here's one way:
render() {
if(!this.props.width) return null; //if it's null, render nothing.
return (
<div className='scene-thumb-parent' style={{width:this.props.width, left:this.props.left}}>
<Card className={this.props.selected?'scene-thumb-selected':'scene-thumb'}>
<span>Hello world!</span>
</Card>
</div>
);
}

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