How to Dynamically Create Many Similar CSS Classes with Sass

Originally posted on my blog.

Let's say you allow 5 sizes of icons in your web application and they're in 6-pixel increments: 12, 18, 24, 30, and 36. Your Sass file might have something like the following to handle this:

.Icon {
  &--size-12 {
    width: 12px;
    height: 12px;
    font-size: 12px;
  }

  &--size-18 {
    width: 18px;
    height: 18px;
    font-size: 18px;
  }

  &--size-24 {
    width: 24px;
    height: 24px;
    font-size: 24px;
  }

  &--size-30 {
    width: 30px;
    height: 30px;
    font-size: 30px;
  }

  &--size-36 {
    width: 36px;
    height: 36px;
    font-size: 36px;
  }
}

These all look really similar, right? The class names all have the same format, and each one sets a width, height, and font-size to be the same thing. Would you believe me if I told you that it's possible to dynamically create blocks of CSS for class names in Sass?

Well, believe me! It's true!

Here's one way you can introduce a @for to do this:

.Icon {
  @for $i from 1 through 5 {
    $base-size: 12;
    $increment: 6;
    $calculated-size: $base-size + ($i * $increment);

    &--size-#{$calculated-size} {
      width: #{$calculated-size}px;
      height: #{$calculated-size}px;
      font-size: #{$calculated-size}px;
    }
  }
}

What if you don't have even increments, though? You can also loop through an array of values like this:

$icon-sizes: 12, 16, 32, 48;

.Icon {
  @each $size in $icon-sizes {
    &--size-#{$size} {
      width: #{size}px;
      height: #{size}px;
      font-size: #{size}px;
    }
  }
}

---

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Comments

[i. welch canavan]

love this trick!

maps combined with @each loops can also DRY up your code:

$gutter-column-sizes: (
    none: 0,
    sm: $unit / 6,
    md: $unit / 4,
    lg: $unit / 2,
    xl: $unit,
);

@each $gutter-column-size-key, $gutter-column-size-value in $gutter-column-sizes {
    .gutter-column--#{$gutter-column-size-key} {
        padding-inline-start: $gutter-column-size-value;
        padding-inline-end: $gutter-column-size-value;
    }
}

[Jonathan Silvestri]

I haven't used SASS in a long time but it has for loops now?! damn

[Ajay Marathe]

Wow, that was helpful 🙏

[Anil Kumar Khandei]

wow we can simplify css so much!!

[Seanmclem]

SCSS is really a bag of tricks I need to learn more about

[Ashlee (she/her)]

Same!! 😄