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A guide to using Tailwind v1.0 and Purge CSS with EmberJS
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README.md

Ember.js, Tailwind 1.0 and PurgeCSS working example

Background

An excellent Ember addon ember-cli-tailwind already exists which wraps Tailwind CSS and provides easy integration in an Ember application.

However, although Tailwind itself has recently released v1.0 with some key differences and updates the addon currently includes a specific pre v1.0 version of Tailwind.

Additionally, PurgeCSS—which is designed to remove unused CSS automatically and very useful considering the Tailwind approach to CSS—is not straightforward to implement when using the addon.

For these reasons it may be useful to include Tailwind and PurgeCSS without the use of an addon.

This repo provides a working example and guide to adding it to a project, each step as a commit.

Very quick start

I've written up in depth below each step of the process but if you just want to quickly get it running here is a very short guide to get you started.

New project

ember new your-project --yarn
cd your-project

Install PostCSS and plugins

yarn add ember-cli-postcss tailwindcss postcss-import @fullhuman/postcss-purgecss -D

Generate Tailwind configuration file

mkdir app/tailwind
npx tailwind init app/tailwind/config.js --full

Add this to the top of the file removes the no-undef linting error

/*global module*/

Note: you probably don't want to add --full in a real project.

Update build pipeline to include plugins

// ember-cli-build.js
'use strict';

const EmberApp = require('ember-cli/lib/broccoli/ember-app');
const isProduction = EmberApp.env() === 'production';

const purgeCSS = {
  module: require('@fullhuman/postcss-purgecss'),
  options: {
    content: [
      // add extra paths here for components/controllers which include tailwind classes
      './app/index.html',
      './app/templates/**/*.hbs'
    ],
    defaultExtractor: content => content.match(/[A-Za-z0-9-_:/]+/g) || []
  }
}

module.exports = function(defaults) {
  let app = new EmberApp(defaults, {
    postcssOptions: {
      compile: {
        plugins: [
          require('postcss-import'),
          require('tailwindcss')('./app/tailwind/config.js'),
          ...isProduction ? [purgeCSS] : []
        ]
      }
    }
  });
  return app.toTree();
};

Create new CSS files and import Tailwind

Create app/styles/components.css and app/styles/utilities.css then update app.css

@import "tailwindcss/base";

@import "tailwindcss/components";
@import "components.css";

@import "tailwindcss/utilities";
@import "utilities.css";

Now you can start to add Tailwind classes to your project, add additional configuration including custom components and utilities.

A detailed explanation of each step and why continues below


Creating a new Ember project

Assuming you already have yarn and ember-cli installed.

ember new emberjs-tailwind-purgecss --yarn

Installing PostCSS

In the Tailwind installation guide it explains

For most projects, you'll want to add Tailwind as a PostCSS plugin in your build chain.

Luckily, a PostCSS addon already exists for Ember, Ember CLI Postcss

It can be installed with

ember install ember-cli-postcss

On it's own this doesn't do much but allows PostCSS plugins to be included in the build pipeline.

Installing Tailwind

Installing package

In our case we want to start with Tailwind, so following the Tailwind installation guide first we install the package from npm (using yarn).

yarn add tailwindcss --dev

Adding directives

Then add the directives to styles/app.css.

@tailwind base;
@tailwind components;
@tailwind utilities;

Including in the build pipeline

The final step is to include Tailwind in the list of PostCSS plugins in ember-cli-build.js

// ember-cli-build.js
'use strict';

const EmberApp = require('ember-cli/lib/broccoli/ember-app');

module.exports = function(defaults) {
  let app = new EmberApp(defaults, {
    postcssOptions: {
      compile: {
        plugins: [
          require('tailwindcss')
        ]
      }
    }
  });
  return app.toTree();
};

This is even helpfully documented in the PostCSS installation guide.

After updating templates/application.hbs to include some Tailwind classes it shows that it is working correctly.

<section class="container mx-auto mt-4">
  <h1 class="text-2xl text-red-500">Example title using Tailwind</h1>
  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.</p>
</section>

{{outlet}}

Customizing Tailwind

This approach works, but is the most basic way of including Tailwind. Usually you'll want to customize the configuration to suit your project.

This is explained in detail in the Tailwind Configuration guide.

Generate configuration file

The first step is to generate a configuration file.

As we want the application to rebuild after changes to the configuration file instead of using the Ember /config directory instead we will create it in a tailwind directory in the app directory so it gets watched when changes are made automatically.

In this example we are going to include the full configuration (whereas in reality, you should start as minimal as possible — but this is useful for testing this example).

mkdir app/tailwind
npx tailwind init app/tailwind/config.js --full

Which should result in something like this

✅ Created Tailwind config file: app/tailwind/config.js

Add this to the top of the file removes the no-undef linting error

/*global module*/

Updating path to configuration in build pipeline

As per the configuration guides update the plugin to include this new path.

// ember-cli-build.js
'use strict';

const EmberApp = require('ember-cli/lib/broccoli/ember-app');

module.exports = function(defaults) {
  let app = new EmberApp(defaults, {
    postcssOptions: {
      compile: {
        plugins: [
          require('tailwindcss')('./app/tailwind/config.js')
        ]
      }
    }
  });
  return app.toTree();
};

Now adding a custom color to the configuration and including it in template will work as expected.

Adding components and utilities

The addon ember-cli-tailwind allows for the easy creation of Tailwind utilities and components.

Both of which are integral to working with Tailwind.

While with our current solution it is possible to add them directly to the app.css file pretty easily (int he right place) splitting them up into separate files would make a cleaner and more modular approach like ember-cli-tailwind does.

Installing PostCSS

To do that we need to now include postcss-import which is a plugin to inline @import rules content.

yarn add postcss-import -D

Updating configuration

After installing we need to update the app.css and ember-cli-build.js to reflect this change.

// ember-cli-build.js
'use strict';

const EmberApp = require('ember-cli/lib/broccoli/ember-app');

module.exports = function(defaults) {
  let app = new EmberApp(defaults, {
    postcssOptions: {
      compile: {
        plugins: [
          require('postcss-import'),
          require('tailwindcss')('./app/tailwind/config.js')
        ]
      }
    }
  });
  return app.toTree();
};

It may be worth pointing out that although this worked for me there has been discussion about also the need to include the node_modules path in the configuration.

Updating CSS importing

For the app.css file some changes are needed to the way the tailwind files are imported and after creating two new files components.css and utilities.css they can be imported (in the right order) too.

This approach of switching from @tailwind directives to @import for postcss-import is explained in the Tailwind documentation on using CSS.

@import "tailwindcss/base";

@import "tailwindcss/components";
@import "components.css";

@import "tailwindcss/utilities";
@import "utilities.css";

Making these changes now means that utilities and components can be easily added and used in your application.

Purging unused CSS

Now that Tailwind is set up and working correctly the final step is to remove all the unused CSS selectors from the outputted CSS to reduce unnecessary filesize.

If you checked your project.css file you would see lots of unused CSS selectors, we want to automate the process of removing them from the outputted CSS.

To do this we can use another library called PurgeCSS.

Installing PurgeCSS

yarn add @fullhuman/postcss-purgecss -D

Basic configuration

Then update ember-cli-build.js to include it in the build pipeline.

'use strict';

const EmberApp = require('ember-cli/lib/broccoli/ember-app');

module.exports = function(defaults) {
  let app = new EmberApp(defaults, {
    postcssOptions: {
      compile: {
        plugins: [
          require('postcss-import'),
          require('tailwindcss')('./app/tailwind/config.js'),
          {
            module: require('@fullhuman/postcss-purgecss'),
            options: {
              content: [
                // add extra paths here for components/controllers which include tailwind classes
                './app/index.html',
                './app/templates/**/*.hbs'
              ]
            }
          }
        ]
      }
    }
  });
  return app.toTree();
};

This should now only include selectors if they have been found in the app/index.html or template files.

Extra paths should be added if you have included selectors in components files or elsewhere in your project.

Improved configuration

Although this does work it there are two main issues

  • it slows down the development cycle (rebuilding CSS with only included classes every time)
  • it misses some Tailwind specific characters, like : in it's string matching.

We can fix this by adding an extractor and conditionally including PurgeCSS in production only.

The Tailwind guides on controlling file size help with this configuration.

// ember-cli-build.js
'use strict';

const EmberApp = require('ember-cli/lib/broccoli/ember-app');
const isProduction = EmberApp.env() === 'production';

const purgeCSS = {
  module: require('@fullhuman/postcss-purgecss'),
  options: {
    content: [
      // add extra paths here for components/controllers which include tailwind classes
      './app/index.html',
      './app/templates/**/*.hbs'
    ],
    defaultExtractor: content => content.match(/[A-Za-z0-9-_:/]+/g) || []
  }
}

module.exports = function(defaults) {
  let app = new EmberApp(defaults, {
    postcssOptions: {
      compile: {
        plugins: [
          require('postcss-import'),
          require('tailwindcss')('./app/tailwind/config.js'),
          ...isProduction ? [purgeCSS] : []
        ]
      }
    }
  });
  return app.toTree();
};

This final configuration now should match all standard Tailwind selectors and only run purgeCSS when building for production.

What else?

In Ed Faulkner's example he included join for the paths.

my guess is that they’re relative to the current working directory. So they will work as long as people type ember at the project root. But won’t work if you happen to invoke the ember command from a subdirectory of your project.

So you may want to update the paths to use join instead if that is an issue for you.

If you have an questions or issues with this please feel free to raise an issue on this project, I'd love to hear your experiences.

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