CSS pre-processors, what are they and should we use them now?

CSS preprocessors, what are they and should we use them now?

Have you seen the css inside css?

Have you seen css with variables?

Wondered css getting complex to look that it used to be!

If NO! It’s Time to Explore.

If YES! Hello, my friend, they are CSS Preprocessors.

Defining CSS Preprocessor

A CSS preprocessor is a type of scripting language that enhances the capabilities of CSS (Cascading Style Sheets) by adding new features, and then transforms it into standard CSS. The primary function of a CSS preprocessor is to provide additional features, such as mixins, nested selectors, and inheritance selectors, that are not available in pure CSS. These features enhance the readability and maintainability of the CSS structure. Numerous CSS preprocessors are available such as SASS, STYLUS, LESS, etc each with its own set of unique features.

However, browsers can’t read CSS Preprocessor code, so it needs to be converted into regular CSS code for them to understand. This prevents compatibility problems across different browsers. Despite each Preprocessor having its own syntax, they all end up being converted to the same regular CSS code.

Before jumping into individual css preprocessors, let’s talk about the basic features of the CSS preprocessor.

Features of CSS Preprocessor

  1. Variables: Preprocessors allow developers to use variables in their CSS code. This means that developers can define a value once and use it multiple times throughout their stylesheet. This can save a lot of time and reduce the risk of errors when making changes.
  1. Nesting: Preprocessors allow developers to nest CSS rules inside other rules, which makes the code more organized and easier to read.
  1. Mixins: Mixins are reusable pieces of code that can be included in other CSS rules. This can save a lot of time and make the code more maintainable.
  1. Functions: Preprocessors allow developers to use functions to perform calculations, manipulate colors, and generate dynamic values.
  1. Modularity: Preprocessors allow developers to organize their code into modules, which makes it easier to manage and maintain.
  1. Compatibility: Preprocessors can generate standard CSS code that can be used in any browser, so there is no need to worry about browser compatibility issues.

After knowing the features do we feel like using them?

It’s a debate for now. Looks interesting but since we know we have many features in css, we might question why use them!

To answer to Whys!

Why Should We Use CSS Preprocessor?

There are several reasons why you might want to use a CSS preprocessor:

  1. Timesaving: A CSS preprocessor can help you save time by reducing the amount of repetitive code you need to write. It allows you to define variables, mixins, and functions that you can reuse throughout your CSS code.
  1. Better Organisation & Maintainability: By using a preprocessor, you can make your CSS code more organized and easier to maintain. You can use nested selectors, which helps you to keep your styles organized and easier to read.
  1. Cross-browser compatibility: CSS preprocessors can help you to write cross-browser compatible code by automatically adding vendor prefixes to your styles.
  1. More functionality: CSS preprocessors offer more functionality than traditional CSS. For example, you can use mathematical operations, conditional statements, and loops to create more dynamic styles.
  1. Better teamwork: CSS preprocessors can help you work better in teams. By using a preprocessor, you can share variables, mixins, and functions with your team, which makes it easier to maintain consistency across your stylesheets.

Overall, CSS preprocessors can help developers write more efficient, maintainable, and scalable CSS code, and can save a lot of time and effort in the long run. They make it easier to work in teams.

Now, we know features and reasons why we use CSS preprocessors. Let’s look briefly at a few of the css preprocessors.

Common CSS preprocessors

There are few css preprocessors introduced since 2006. Css preprocessor ‘sass’ was introduced in 2006 which is the oldest. Many css preprocessors like Less (Leaner Style Sheets), Stylus, PostCSS and CSS-Crush has been introduced. The most common and popular preprocessors used today are SCSS/SASS, Less and Stylus.

Let’s discuss these popular ones in brief.

Sass (Syntactically Awesome Style Sheets)

Sass is one of the most popular and oldest CSS preprocessors and is known for its features like variables, nesting, mixins, and functions. Sass was release in 2006 by Natalie Weizenbaum and Hampton Catlin.

There are two syntaxes available in Sass. The older syntax, which is based on indentation, does not use semicolons or curly brackets in the code and has a file extension of .sass. The newer and more commonly used syntax is known as scss and has a file extension of .scss. It follows the standard CSS syntax and includes the use of braces and semicolons.

Basic example of Saas:

Fig 1. SCSS showing feature of variables

Fig 1. SCSS showing feature of variables

Fig 2. Scss showing feature of nesting.

If you want to explore and try on your own, you can go to the SCSS documentation of SCSS.

And you want to play around with scss you can go to link below:


Sass boasts an extensive community of developers, with numerous tools and libraries at their disposal. Furthermore, both Bootstrap and Zurb Foundation, which are popular frontend frameworks, have been developed using Sass.

LESS: Leaner Style Sheets

LESS, is a CSS preprocessor, which was introduced in 2009, three years after the introduction of Sass. LESS was inspired by Sass and integrated several of its features, including mixins, variables, and nesting. Subsequently, LESS also influenced Sass, with SCSS incorporating some of LESS’s syntax.

The LESS preprocessor is essentially a JavaScript library that enhances the capabilities of CSS. Node.js is required to install and execute the LESS compiler because it is written in JavaScript. However, it is also feasible to compile LESS on the fly by including .less files and the LESS converter in the <head> section of an HTML page. The .less file extension is used by LESS.

Example of LESS

Fig 3. Figure showing variables in LESS
Fig 4. Figure showing nesting with the media queries in LESS.

If you want to explore you can go to the LESS documentation.

And you want to play around with less you can go to link below:



Stylus was created in 2010 by TJ Holowaychuk, who was previously a Node.js developer. It is a Node.js-focused preprocessor and was influenced by both Sass and LESS. Stylus is recognized for its minimalistic approach and combines the strong logical capabilities of Sass with the easy-to-use setup of LESS. Unlike other preprocessors, Stylus allows for optional use of braces, colons, and semicolons. The file extension used by Stylus is .styl.

Stylus has mixin libraries like Nib and Ride.css that offer pre-made cross-browser mixins. While Stylus frameworks like Basis and Kouto Swiss may not be as popular as Bootstrap or Foundation, they are still considered good options. Companies like Coursera, Livestorm, Accenture, Zenchef, and HackerEarth are notable corporate users of Stylus.

Glimpse of Stylus Syntax:

Fig 5. Variables in Stylus
Fig 6: Nesting in Stylus

Learn Stylus Here: https://stylus-lang.com/

CSS Preprocessors Today

SASS is currently the most advanced, stable, and powerful extension language available in the market, having been released in 2006 and having been in use for over 15 years.

Fig 7. Stats showing the opinion of people on preprocessor over time.

This is the survey report of CSS preprocessors, that splits positive vs negative experiences on both sides of the central axis.

  • Upon analyzing the survey results, it was discovered that 75.9% of the respondents preferred to use Sass as their CSS processing tool, with an additional 4.5% expressing interest in it.
  • Then the second most preference is for LESS. but here it is opposite to sass. Most of them are not interested and also would not like to use it.
  • However, compared to Stylus, Less is more popular than that and also 18.8% of people are using it. 

In this survey graph about the CSS preprocessors, from 2019 to 2021. Sass is the most popular CSS preprocessor nowadays and the least used is stylus. Only a moderate change has happened in the past few years. 

What are the drawbacks of using a CSS preprocessor?

CSS preprocessors have gained popularity in recent times due to their ability to efficiently reuse code and reduce the size of source files. However, it is important to note that the use of preprocessors comes with certain drawbacks, such as the need for a compilation step and potential errors that may arise due to a minimum knowledge.

One of the primary benefits of CSS preprocessors is their ability to reuse code, which can help reduce the size of source files and make it easier to maintain a consistent style throughout a project. However, this can also lead to longer troubleshooting times if errors do occur, as it may take longer to identify where the problem is located.

Additionally, since the browser does not read the more advanced version of CSS produced by preprocessors, it is necessary to compile the code into regular CSS before the style can be displayed. This compilation step can be time-consuming and may add to the overall completion time of a request.

It is worth noting that while CSS preprocessors are widely used, there may be a knowledge gap among some developers, which can lead to errors or other issues. Therefore, it is important for professionals working with preprocessors to have a thorough understanding of the technology and to stay up to date with best practices in order to avoid potential pitfalls.

To pin point the drawbacks, here are the list of them:

  • Debugging becomes more difficult.
  • Compilation can significantly slow down the development process.
  • CSS files generated by preprocessors can become quite large.
  • Maintenance and over-engineering can be a challenge.
  • Deciding whether or not to save generated files can be a concern.
  • Capability and understanding of preprocessors may be required.
  • Availability of knowledge among developers may be limited.

By now we have taken a brief tour on the preprocessor and explored them a bit. What do you think now? Will you use them or walk away from them?

Should we use it!

Stepping into the world of front-end web development we should all have to learn new things and update the current tools and trends in the market. 

As a newbie in web design who has only learned CSS for 5 months, my answer is NO. Not that it’s bad, just that I’m not planning to start using it right away at this stage. There is a chance you might get in trouble.

Since the syntax of CSS and CSS preprocessor are different but similar, we may feel confused or even misuse them when we are not yet familiar with them. All CSS pre-processors have many extension functions containing programming concepts.

I am not saying that you have to learn all the CSS. But you should have to learn CSS properly and also you have to be confident in debugging and create a proper good website all by yourself at least 5. You should have to learn the basics of programming and also you have to be confident about debugging the code that we have done using CSS preprocessors. Because otherwise there is a chance to get the code errors. 

Also, if you are working on a smaller size of project, I would suggest not using the CSS preprocessor. But in the big projects where you have multiple files and multiple people to work on the same project then the CSS preprocessors are more beneficial.


CSS preprocessors, such as Scss, Stylus, and Less, have gained immense popularity in recent years, and are now widely used by frameworks like Bootstrap, Nib, and others. These preprocessors offer advanced features that were not available in CSS earlier, making them a handy tool for developers.

While these preprocessors have similarities, they are unique in their own way, and understanding one can make it easier to understand the others. Therefore, it is essential to explore and learn about each preprocessor and choose the one that best fits the requirements of your project.

It is worth noting that CSS preprocessors were more widely used before the introduction of advanced CSS features such as variables and custom CSS. However, they still have significant benefits and can be a valuable addition to any development workflow. It is important to be wise while selecting a preprocessor and consider the specific use case and project requirements before deciding. By doing so, developers can make the most of these powerful tools and streamline their development process.

References & Exploration

Shero Commerce[Online] : https://sherocommerce.com/what-is-a-css-preprocessors-why-use-them/ [Accessed Feb 2023]

Raygun [Online] : https://raygun.com/blog/css-preprocessors-examples/ [Accessed Feb 2023]

Lambdatest [Online] : https://www.lambdatest.com/blog/css-preprocessors-sass-vs-less-vs-stylus-with-examples/ [accessed Feb 2023]

Sass [Online: Official site of sass] : https://sass-lang.com/ [accessed Feb 2023]

Less [Online: Official site of less] : https://lesscss.org/ [accessed Feb 2023]

Stylus [Online: Official site of stylus] : https://stylus-lang.com/ [accessed Feb 2023]

KeyCDN [Online] : https://www.keycdn.com/blog/sass-vs-less [accessed Feb 2023]

Medium [Online] : https://medium.com/analytics-vidhya/css-preprocessors-what-is-this-now-bae60c0bfedb [accessed Feb 2023]