Custom Theme | Dart SASS + Node 16

If you have an existing project, and are looking to change your site to use Dart SASS, give this guide a read for some helpful commands, common issues and solutions.

If you are starting a new project, there are also some helpful steps included for you.

Changing your project to use Dart SASS with Node 16

If you are updating an existing Node 14 project, that uses npm node-sass, you will need to make a few changes before updating to Node 16 and npm sass.

What is the difference? Read these first - npm: node-sass vs npm: sass

Delete package-lock.json then edit the package.json file, in theme root.
1. Add or edit what you need. Here’s a helpful example with explanation: Node.js version control in Drupal themes
Run the following, suggested commands:
1. npm cache clean --force
2. nvm ls
  Prints the node versions installed on your machine & the current node version you're using.
3. nvm use 16
4. npm install
  1. If you try to run npm install however, it will error out due to you trying to use node-sass.
  2. npm uninstall node-sass
    1. Removes node-sass
  3. npm install sass or npm i sass --save or npm install node-sass@npm:sass
    1. Replaces node-sass with the newer sass dependency.
5. npm install
  1. Should run as expected, if not - follow the errors/warnings as resolve as needed. We have some notes below on known issues.
6. npm cache clean --force
7. If you run into a problem, and want to try again:
  1. rm -r node_modules
    This will remove the node_modules folder in your repository. If you are using Webpack, you can also remove the dist folder using rm -r dist and re-build your repository.

Note: If the commands are not automatically altering your package.json file, you may need to edit it manually.

Know issues, and Potential warning or errors known with changing Node to version 16 and Dart SASS:

Node-Sass - Warning: LibSass and Node Sass are deprecated. While they will continue to receive maintenance releases indefinitely, there are no plans to add additional features or compatibility with any new CSS or Sass features. Projects that still use it should move onto Dart Sass.
Are you running a M1 mac? ARM64 isn't supported by any version of node-sass right now. If you try to run npm install after switching to Node 16 - it will error out. See above for details.
Deprecation Warning: $weight: Passing a number without unit % (##) is deprecated.
Deprecation Warning: Using / for division outside of calc() is deprecated and will be removed in Dart Sass 2.0.0.
- Here’s a helpful explanation - Deprecation Warning: Using / for division outside of calc() is deprecated and will be removed in Dart Sass 2.0.0
Can't install node-sass@6 for node v16
error /node_modules/node-sass: Command failed
https://www.drupal.org/project/bootstrap_sass/issues/3259490
https://www.drupal.org/project/drupal/issues/3261734#comment-14421915
Error with node-sass when running npm install
Possibly relevant:
We are using npm: jpegtran-bin , but should be using npm: imagemin-jpegtran

Math changes required when using Dart Sass - Examples:

// This:
@function strip-unit($num) {
  @return $num / ($num * 0 + 1);
}

// Should become this:
@use "sass:math";

@function strip-unit($num) {
  @return math.div($num, ($num * 0 + 1));
}

// This:
$browser-context: 16;
@function rem($pixels, $context: $browser-context) {
  @return #{strip-unit($pixels)/$context}rem;
}

// Should become this:
@use "sass:math";

$browser-context: 16;
@function rem($pixels, $context: $browser-context) {
  @return #{math.div(strip-unit($pixels), $context)}rem;
}

// These:
$base-space: 1rem; // 16px
$space-10: $base-space / 2; // 8px
$space-20: $base-space * 2; // 32px

// Should become like these:
$base-space: 1rem; //16px
$space-10: calc($base-space / 2); // 8px
$space-20: calc($base-space * 2); // 32px