I wanted to play with all different types of styling methods in GatsbyJS. In my project, I have three types of implementing stylings, global CSS, CSS Modules and CSS-in-JS(styled-component). Everything works as expected. But, when I build the project with gatsby build and open one of the index.html where I did CSS-in-js I see that there is a CSS file in data-href tag inside. When I open it, It contains all the CSS stylings of my project. But I didn't even import it to the component where I did CSS-in-js. Why would something like this happen? Why stylings from module.css are being referred inside this file.
I use React, scss.
I have main scss file with mixins, variables, extends etc. Currently if i want use mixins or variable i need to #import './global.scss'; in each component directly where i want to use it. But most of the time i need these styles in almost all components global.scss.
How i can make global.scss visible for all components without repeating import in each component directly?
Thanks.
there is no such possibility in sass.
The solutions are:
The first and the easiest:
Just include #import in all sass files, it is not bad practice as you will always have control of all vars that are imported in each file in your app.
The second
While building you app via webpack you can find all sass files(that are not started with underscore) in your project and include you import in it.
In a React app, we usually import CSS files into the JavaScript components.
I thought this way we inject the CSS into the final JavaScript build.
However, it seems that React (at least create-react-app) still generates separate CSS files.
Why is that?
Is there any way to force CSS stylings to be part of the final r? Kind of CSS-In-JS?
You should eject the create-react-app and change webpack config file (style-loader similar question) to not create separate file for css bundle or use html-inline-css-webpack-plugin.
my question is little subjective.
so the scenario is like- I have n numbers of react components. Each
components have its respective css file. There are few common css files which are inside
assets/css/ files. I am simply importing common css file to my react component css file if needed.
for Example:-
There is a assets/css/color.css file which is common and used by few of components. I am importing assets/css/color.css to those css files which needs it. This way I am importing assets/css/color.css many times to different css files.
My question is- When webpack starts bundling the code how does it handle multiple import of same css file? Does importing same css files at many places leads to redundancy in bundle file?
The answer given by How does webpack handle multiple files importing the same module React imply that webpack will only bundle each library only once.
That's true for JS modules. Each module is embeded only once and webpack reuse the instance where appropriate.
However if you include another file inside that file, then it's up to how the css webpack module manage it.
For raw CSS, I think the file will get included only once as all is managed directly by webpack.
However if you use the sass loader and import some other sass file from your first sass file like that:
1.js File -> includes a.sass file -> #import another.sass file
2.js File -> includes b.sass file -> #import another.sass file
Then if another.sass file generate some classes definition, you'll see that these classes appear multiple times in the output. This is because webpack doesn't know about the duplication because it's handled at the sass loader level.
I'm trying to find a solution to this problem:
I'm using a template with different css includes based on page, ex:
Login uses login.css
Home uses home.css
If I load both css the login page is broken, because styles are overwritten by home.css
So I need to load or require login.css if the route or the component is Login and the other one when is Home.
If I load both webpack builds a global css with both files, and everything is broken...
I tried to require the css in componentDidMount, but I think that is not the way :)
Thanks in advance
It sounds like both these styles are quite specific to the pages, so why not simply namespace them?
Within your templates, have a .login/.home class, and use this as the namespace within the css. If you're using sass, this is as simple as wrapping all the sass in the class. Otherwise, you can go through and add the class to the beginning of all the elements/clases.
First of all, you shouldn't have any problems if you use different css classes for your views and just style the elements based on those classes.
The best way to load css in react is to do it by components, if you got a component login.jsx, in your styles folder (or whatever folder you're using to hold your styles) create a sass partial _login.scss and add the css selectors and styles for that given component, and do that for every component in your react application.
Then you just include those partials into a main.scss file and that's the file you want to load into your react app.
Here's an example of a main.scss file with some sass partials.
#import 'base/variables';
#import 'base/defaults';
#import 'components/login';
#import 'components/home';
That's a good and clean way to work with styles in react, of course you will need to configure your webpack in order to get sass to work in your application.
Take a look at this and this for more info.
This is a more generic approach to combine CSS files, without depending on technologies like SASS or reactjs.
I assume, if you combine the two CSS files, you are using Grunt or similar tool, to automate that task. So automatically updating the CSS files should be OK for you, even though they are from an external source and you want to use updated versions without making manual changes.
I also assume, you are using classes to style your pages, so there are no tag based styles in your CSS. Because you cannot rename the tags in the CSS file without braking it or make larger changes to your code.
If my assumptions are true, you could use something like grunt-css-prefix. It can add prefixes to your CSS classes for the login page, like in this snippet.
Original CSS file content:
.foo,
.bar,
h1 {
display: none;
}
CSS file content after running the Grunt script:
.login-foo,
.login-bar,
h1 {
display: none;
}
Just use the login-foo like class names in your Login-HTML and you are good to go.
For more details on how to use grunt-css-prefix, please have a look at https://www.npmjs.com/package/grunt-css-prefix.