Frontend Interview: 26 SCSS Questions and Answers

Frontend development was all about HTML, CSS and Javascript before. Now, we have a vast of amount tools of these languages. One of them is SCSS, which is a popular extension of CSS that introduces features like variables, nesting, mixins, and more to make styling easier.

If you’re preparing for an frontend interview that involves SCSS, here are 25 potential questions and answers to help you get ready.

Table of Contents

1. What is SCSS?

SCSS, or Sassy CSS, is a CSS preprocessor that extends the capabilities of standard CSS. It introduces features like variables, nesting, mixins, and more, which enhance code organization and maintainability.

2. What’s the difference between SCSS and regular CSS?

Regular CSS is the standard stylesheet language used to define the presentation of web content. SCSS is a superset of CSS, which means that any valid CSS is also valid SCSS. However, SCSS introduces features like nesting, variables, and mixins that aren’t present in regular CSS.

3. How do you comment in SCSS?

In SCSS, you can use the same comment syntax as in CSS:

/* This is a single-line comment */

/*
   This is a
   multi-line comment
*/

4. What are variables in SCSS?

Variables in SCSS allow you to store and reuse values throughout your stylesheet. They are defined using the $ symbol:

$primary-color: #007bff;

.element {
  color: $primary-color;
}

5. Explain nesting in SCSS.

Nesting in SCSS allows you to nest selectors within one another, making the code more readable:

.nav {
  ul {
    margin: 0;
    padding: 0;
    
    li {
      list-style: none;
    }
  }
}

6. How do you compile SCSS code into regular CSS?

To compile SCSS code into regular CSS, you can use the command line or build tools like Node.js-based Sass or various GUI applications. For command-line compilation, you can use a command like:

sass input.scss output.css

7. What is the `&` symbol used for in SCSS?

The & symbol in SCSS is a special character that refers to the parent selector. It’s commonly used in conjunction with pseudo-classes and pseudo-elements:

.button {
  &::hover {
    background-color: #ffcc00;
  }
}

8. How can you perform mathematical operations in SCSS?

SCSS allows you to perform arithmetic operations directly within your styles:

$base-font-size: 16px;

.element {
  font-size: $base-font-size * 1.5;
}

9. What is the `@extend` directive?

The @extend directive in SCSS allows you to share a set of properties from one selector to another, reducing code duplication.

.button-base {
  padding: 10px;
  background-color: #007bff;
}

.primary-button {
  @extend .button-base;
  color: #fff;
}

10. Explain the concept of placeholders.

Placeholders are defined using % in SCSS and serve as reusable styles that can be extended using the @extend directive. They are not output in the final CSS:

%shared-style {
  border: 1px solid #ddd;
}

.element1 {
  @extend %shared-style;
}

.element2 {
  @extend %shared-style;
}

11. How can you import SCSS files into each other?

In SCSS, you can use the @import rule to import other SCSS files. The imported file’s styles will be merged into the current file:

@import 'variables';
@import 'buttons';

12. How do you use the `@mixin` directive?

The @mixin directive in SCSS defines a reusable set of styles that can be included in other selectors using the @include directive:

@mixin border-radius($radius) {
  border-radius: $radius;
}

.element {
  @include border-radius(5px);
}

13. What is the difference between `@mixin` and `@function`?

@mixin is used to define a reusable set of styles, while @function is used to define a reusable piece of code that returns a value. Functions are used for calculations or dynamic values.

14. How do you use loops in SCSS?

SCSS provides loops that can be used to generate repetitive code. For example, the @for loop:

@for $i from 1 through 3 {
  .element-#{$i} {
    width: 100px * $i;
  }
}

15. What is the purpose of the `@each` directive?

The @each directive in SCSS is used to loop through a list or map and generate styles based on its values. It’s useful for generating multiple similar styles.

16. What is the `@at-root` rule used for?

The @at-root rule in SCSS allows you to break out of nesting and generate styles at the root level. This can be useful when you want to avoid generating overly specific selectors.

17. What is the significance of the `!default` flag in SCSS variables?

The !default flag in SCSS variables allows you to set a default value that can be overridden if the variable is already defined.

Example:

$primary-color: blue !default;

18. What is interpolation in SCSS?

Interpolation in SCSS is used to inject dynamic values into strings or selectors using #{}:

$property: color;
$color: red;

.element {
  #{$property}: $color;
}

19. Explain the use of the `@debug` directive.

The @debug directive in SCSS outputs the value of a variable or expression to the console, helping in debugging and understanding how the code is working.

20. How can you generate automatic CSS vendor prefixes in SCSS?

SCSS doesn’t provide automatic vendor prefixing by default, but you can use tools like Autoprefixer to add prefixes based on browser compatibility.

21. What is the `@if` directive used for in SCSS?

The @if directive in SCSS allows you to conditionally apply styles based on a specified condition:

$color: red;

.element {
  @if $color == red {
    background-color: $color;
  } @else {
    background-color: blue;
  }
}

22. Explain the concept of a map in SCSS.

A map in SCSS is a data structure that holds key-value pairs. It’s used to store related values and is particularly useful for creating dynamic styles.

$colors: (
  primary: #3498db,
  secondary: #e74c3c
);

23. What are the `@warn` and `@error` directives used for?

The @warn directive in SCSS generates a warning message in the console, while the @error directive generates an error message and stops compilation. They are used for debugging and handling potential issues.

24. How do you perform color operations in SCSS?

SCSS allows you to perform color operations like mixing, darkening, lightening, etc., using built-in functions like mix(), darken(), lighten(), etc.

25. What is the purpose of the `unquote()` function?

The unquote() function in SCSS is used to remove the quotes from a string, which can be helpful when you need to use a string value without quotes.

26. How can you organize SCSS code for better maintainability?

You can organize SCSS code by using partials, creating separate files for components, utilities, and variables. This makes your codebase more modular and easier to manage.

Conclusion

In conclusion, familiarizing yourself with these SCSS questions and answers will boost your confidence in handling SCSS-related questions in frontend development interviews. Don’t forget to practice your SCSS skills, explore practical examples, and stay updated with the latest SCSS updates to excel in your journey as a frontend developer.

Best of luck!

If you want to learn more about SCSS, then you can check the following articles:

Add SASS Variables Vite Vue Components

Thank you for reading.