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CSS Modules vs Sass: What are the differences?


In website development, both CSS Modules and Sass are popular tools used to enhance the styling of web pages. CSS Modules allows for the creation of local scope for CSS, while Sass is a preprocessor scripting language that extends CSS and provides additional functionalities. Below are the key differences between CSS Modules and Sass.

  1. Naming Conventions: CSS Modules use a unique naming convention where class names are automatically generated, preventing clashes with other elements in the web page. In contrast, Sass does not provide any specific naming convention, allowing developers to use their preferred naming conventions.

  2. Scope: CSS Modules provide local scope for CSS, meaning that classes defined within a component are only applied to that specific component. This encapsulation helps avoid conflicts and ensures that styling is isolated. On the other hand, Sass does not inherently offer local scope, and developers need to manage scoping manually.

  3. Syntax: CSS Modules use standard CSS syntax, making it easy for developers who are already familiar with CSS. It provides a simple way to define stylesheets with class names. In contrast, Sass introduces additional syntax, such as variable declarations, nesting, and mixins, which enhances the capabilities of CSS.

  4. Dependency Management: CSS Modules handle dependencies automatically, with each module taking care of its own dependencies. This reduces the risk of conflicting styles and simplifies the management of stylesheets. Sass, on the other hand, does not handle dependencies automatically, and developers need to manually import and manage dependencies.

  5. Extensibility: Sass offers a broader range of features and functionalities compared to CSS Modules. It provides various programming features like variables, functions, mixins, and inheritance, allowing for code reuse and more advanced styling capabilities. CSS Modules have limited extensibility since they mostly focus on providing local scope.

  6. Compatibility: CSS Modules are supported by most modern browsers without the need for any additional tools or compilation processes. However, Sass requires a compilation step to convert the Sass code into standard CSS before it can be used by the browsers. This extra step might add complexity to the development process and increase build times.

In Summary, CSS Modules and Sass differ in their approach to scoping, naming conventions, syntax, dependency management, extensibility, and compatibility. While CSS Modules provide local scoping and automatic naming conventions, Sass offers a more extensive set of features with additional syntax and requires a compilation step for browser compatibility.

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Originally, I was going to start using Sass with Parcel, but then I learned about Stylus, which looked interesting because it can get the property values of something directly instead of through variables, and PostCSS, which looked interesting because you can customize your Pre/Post-processing. Which tool would you recommend?

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You're not correct with saying "vs Postcss". You're using Less/Sass/Stylus/... to produce "CSS" (maybe extended means it has some future features) and then in any case PostCSS will play (it is shipped with Parcel/NextJS/CRA/...)

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Pros of CSS Modules
Pros of Sass
  • 2
    Static rather than compiled at runtime
  • 613
  • 594
  • 466
    Nested rules
  • 410
  • 300
  • 149
    Modular flexible code
  • 143
    Open source
  • 112
    Selector inheritance
  • 107
  • 96
    Better than cs
  • 5
    Used by Bootstrap
  • 3
    If and for function
  • 2
    Better than less
  • 1
    Inheritance (@extend)
  • 1
    Custom functions

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Cons of CSS Modules
Cons of Sass
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    • 6
      Needs to be compiled

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    - No public GitHub repository available -

    What is CSS Modules?

    It is a CSS file in which all class names and animation names are scoped locally by default. The key words here are scoped locally. With this, your CSS class names become similar to local variables in JavaScript. It goes into the compiler, and CSS comes out the other side.

    What is Sass?

    Sass is an extension of CSS3, adding nested rules, variables, mixins, selector inheritance, and more. It's translated to well-formatted, standard CSS using the command line tool or a web-framework plugin.

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    What companies use CSS Modules?
    What companies use Sass?
    See which teams inside your own company are using CSS Modules or Sass.
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    What tools integrate with CSS Modules?
    What tools integrate with Sass?
      No integrations found

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      What are some alternatives to CSS Modules and Sass?
      Radium is a set of tools to manage inline styles on React elements. It gives you powerful styling capabilities without CSS.
      This methodology was developed at Yandex with the goals in mind that Fast development and long-lasting results for standard projects,A project involves many people,Scalable teams,Code reuse.
      CSS Blocks
      By combining an opinionated authoring system, build-time analysis and rewriting of templates, and a new type of CSS optimizer, css-blocks breathes new power and ease of use into the technologies and best practices that stylesheet developers already know and love.
      Visual primitives for the component age. Use the best bits of ES6 and CSS to style your apps without stress 馃拝
      Emotion is a performant and flexible CSS-in-JS library. Building on many other CSS-in-JS libraries, it allows you to style apps quickly with string or object styles. It has predictable composition to avoid specificity issues with CSS. With source maps and labels, Emotion has a great developer experience and great performance with heavy caching in production.
      See all alternatives