postcss/postcss

Transforming CSS with JS plugins

Andrey Sitnik

@ai

we do not have publish step anymore, it is so great!

Ju Demarque

@dmrqx

Hi! I have a question concerning testing components with Jest that depend on values obtained from a css file (via postcss-modules-values @value variables).

In my configuration I am using identity-obj-proxy for .modules.css files, as recommended, but it also transforms @value declarations to plain name strings with no way of recovering the actual values.

The solution I found was to mock the .module.css file into the component tests, but this way I have to mock it for all the parents of said component as well.

Does this sound "appropriate"? Is there another way of resolving jest warnings that may appear when using @value properties in JS?

Evilebot Tnawi

@evilebottnawi

@ai hi, i want to update postcss-loader to new major release (update deps, drop node@6 and etc), will be great also update postcss too, any ETA for next postcss release?

Andrey Sitnik

@ai

@evilebottnawi there is performance regression in the next release branch and I have no time to investigate it. Release it without waiting for PostCSS. I afraid the best release could be only in month or more

f0x52

@f0x52

Can I get postcss to only namespace a top-level class, and then use nesting without getting those classes namespaced as well?

I'm using it with React and my optimal usecase would be to have everything namespaced on component level, but being able to use normal classnames inside that component

kapilpipaliya

@kapilpipaliya

i am new to postcss. which plugins should i use?

i am using postcss-preset-env now

Ryan Zimmerman

@RyanZim

@kapilpipaliya It depends what you want to do. There's a plugin for just about everything

postcss-preset-env allows you to use new CSS features

kapilpipaliya

@kapilpipaliya

Ryan Zimmerman

@RyanZim

There are other plugins that allow you to do other things not possible with regular, spec CSS

kapilpipaliya

@kapilpipaliya

i want to use latest technologies

which plugins you recommand?

Ryan Zimmerman

@RyanZim

postcss-preset-env is what you're looking for, in that case

kapilpipaliya

@kapilpipaliya

any other plugins i should use?

Ryan Zimmerman

@RyanZim

If you're just looking for modern CSS not yet supported in browsers, postcss-preset-env should get the job done.

kapilpipaliya

@kapilpipaliya

thanks

Ryan Zimmerman

@RyanZim

no problem, stop by anytime, happy to help!

kapilpipaliya

@kapilpipaliya

thank you

Evilebot Tnawi

@evilebottnawi

@ai thanks for answer, also i ahve some problem in npm, can you give me access to npm (https://www.npmjs.com/package/postcss-loader), thanks again

Bogdan Ponomarenko

@b-ponomarenko

Hi everyone! I can't use postcss-mixins plugin with create react app. Steps:

Run npm run eject command

Install postcss plugin and add configuration to webpack config:

require('postcss-mixins', {
           mixins: {
             clearfix: {
               '&::after': {
                 content: '""',
                 display: 'table',
                 clear: 'both'
               }
             }
           }
         })

Use mixin in css:

.App {
@mixin clearfix;

text-align: center;
}

Have error:

./src/App.css (./node_modules/css-loader/dist/cjs.js??ref--6-oneOf-3-1!./node_modules/postcss-loader/src??postcss!./src/App.css)
Syntax error: Undefined mixin clearfix (2:3)

1 | .App {
> 2 |   @mixin clearfix;
 |   ^
3 | 
4 |   text-align: center;

Did anyone have this problem?

Andrey Sitnik

@ai

@evilebottnawi done

Evilebot Tnawi

@evilebottnawi

@ai thanks!

Gavin McFarland

@limitlessloop

Hi, I writing my a design token preprocessor and I’m looking at PostCSS for some inspiration on how to handle plugins in my project. I’ve always thought PostCSS has an interesting plugin architecture.

export default postcss.plugin("postcss-border-align", (opts) => {
    console.log('opts', opts);
    return root => {

    };
});

@ai are you able to explain any on how you thought of this format and briefly how it works? I presume that postcss.plugin() sets a plugin to the postcss api and what the plugin returns is in the callback function.

Andrey Sitnik

@ai

@limitlessloop postcss.plugin is just a syntax sugar to set plugin name in plugin function. A lot of developer forget to set name (or create a non-standard API for their plugin), it reduced user’s UX of using PostCSS with many different plugins

yeap, postcss.plugin callback accept options from user (from PostCSS plugins config like { plugins: [require('postcss-border-align')({ node: 'always' })] }) and return plugin function

plugin function accepts AST root and result and change AST root and\or set warnings to result

Gavin McFarland

@limitlessloop

Thank you for taking the time to explain that.

Are there any occurances in a plugin where you might want to return something other than root? If so how do you detect that, when root is user defined? In my tool users can create data structures, or a rendered template or both and I’m struggling to think what the plugin should look like. At the moment I’m leaning towards being two completely separate things.

For example

mole.plugin('plugin-name', (opts) => {
    return (model, template) => {
        model.user.name = 'Gavin'
        template = 'My name is {{user.name}}'
    }
})

mole.model('model-name', (model) => {
    return model.user.name = 'Gavin'
})

mole.template('template-name', () => {
    return 'My name is {{user.name}}'
})

Andrey Sitnik

@ai

What exact token do we talk about?

and what is model and template in the real case?

(sorry, I work much better with real examples)

Gavin McFarland

@limitlessloop

No worries. I’ll message you seperately so I don’t fill up this room.

Johannes Bernhard Goslar

@ksjogo

Is there some way to recalculate parents after inserting things with atrule.replaceWith and postcss.decl? Autoprefixer crashes on some undefined parents.

Andrey Sitnik

@ai

It should recalc the parents. Maybe we have an issue with code or docs

try to see inside methods, PostCSS AST is very simple

Jonathan Neal

@jonathantneal

Blink has intent to implement CSS Modules. Is that the same as the PostCSS community created standard?

Evilebot Tnawi

@evilebottnawi

And yes and no, we will have css parser and api for working with css on browser side

and pure css-in-js implementation :smile:

Jonathan Neal

@jonathantneal

Is part of the plan to expose the CSS parser?

That’s great news. Now that I understand they are different from what I’m reading right now — I don’t see any mention of a parser let alone a loose parser. I see functionality that reads a CSS file as CSS (not much different from using <link>)

Bohdan Ptyts

@bohdanbirdie

Hey fellas

Jonathan Neal

@jonathantneal

Hello

Bohdan Ptyts

@bohdanbirdie

I wonder if there is a chance that someone can help me with the issue that I'm already struggling for two days
I'm working on the project that is using the https://github.com/gajus/react-css-modules
We're having the app, but also separate repo for the components with pretty much the same webpack config
Due to the development of new additional app that will also use those components we decided to migrate from react-css-modules to recommended https://github.com/gajus/babel-plugin-react-css-modules (same author)
At the moment we're using BEM style with SCSS (so I have those sassy imports like _filename.scss)
Seems like I migrated more or less successfully, but some styles are missing, so it's actually those that are imported inside the SCSS files

They use as example this snippet

"plugins": [
    ["postcss-import-sync2", {
      "path": ["src/styles", "shared/styles"]
    }],
    "postcss-nested"
  ]

I tried to, updated path and etc, but it could not find the imported files

I already tried several import plugins, but it didn't work. It's either failing on the Use process(css).then(cb) to work with async plugins or on Error: Failed to find

I would really appreciate a little bit of help here, will die out of this soon

Snippet from my .babelrc

[
      "react-css-modules",
      {
      "handleMissingStyleName": "warn",
      "generateScopedName": "[local]___[hash:base64:5]",
      "filetypes": {
        ".scss": {
          "syntax": "postcss-scss",
          "plugins": [
            ["postcss-import-sync2", {
              "path": ["lib/scss"],
            }],
            [
              "postcss-nested",
              { "preserveEmpty": true }
            ]
          ]
        }
      }
    }],

Evilebot Tnawi

@evilebottnawi

@jonathantneal under api parser exists, you can get rules and property and values, and some other stuff

Bohdan Ptyts

@bohdanbirdie

And from the webpack SCSS match

{
                        loader: 'postcss-loader?parser=postcss-scss',
                        options: {
                            plugins: [
                                autoprefixer,
                                cssnano(),
                            ],
                        },
                    },

Eric

@sliceofbytes

I have these rules but for some reason it's still removing the items I've listed in ignore
    rules: [
      {
        test   : /\.scss$/,
        loader : 'postcss-loader',
        options: {
          ident  : 'postcss',
          plugins: () => [
            require('postcss-short')(),
            require('postcss-uncss')({
              report:true,
              html: ['src/**/*.html'],
              ignore: ['.scrubBar', '.active', '.locked', '.completed', '.activity-topics-item.active']
            }),
          ]
        }
      }
    ]

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