@each loop over maps in SASS

Introduction

The @each loop helps you repeat styles for many items in a map easily. It saves time and keeps your code neat.

You want to create multiple CSS classes with different colors from a color map.

You need to apply different font sizes to headings stored in a map.

You want to generate button styles for various states stored as key-value pairs.

You have a list of themes with properties and want to create styles for each theme.

Syntax

SASS

@each $key, $value in $map {
  // CSS styles using $key and $value
}

The $key is the map's key (like a name).

The $value is the map's value (like a color or size).

Examples

This creates two button classes with background colors from the map.

SASS

$colors: (primary: #06c, secondary: #ccc);

@each $name, $color in $colors {
  .btn-#{$name} {
    background-color: $color;
  }
}

This sets font sizes for headings named hsmall, hmedium, and hlarge.

SASS

$fonts: (small: 0.8rem, medium: 1rem, large: 1.2rem);

@each $size, $value in $fonts {
  h#{$size} {
    font-size: $value;
  }
}

Sample Program

This code creates three CSS classes: .theme-light, .theme-dark, and .theme-blue. Each class sets a background color from the map. The text color changes to black for the light theme and white for others. Padding, rounded corners, and spacing are added for style.

SASS

@use "sass:map";

$themes: (
  light: #fff,
  dark: #000,
  blue: #00f
);

@each $name, $color in $themes {
  .theme-#{$name} {
    background-color: $color;
    color: if($name == light, #000, #fff);
    padding: 1rem;
    border-radius: 0.5rem;
    margin-bottom: 1rem;
  }
}

Important Notes

Use #{$variable} to insert variables inside selectors or property names.

Maps store pairs like a dictionary: keys and values.

You can use if() inside styles to choose values based on conditions.

Summary

@each loops over map keys and values to create repeated styles.

Use $key and $value to access each pair inside the loop.

This helps keep your CSS DRY (Don't Repeat Yourself) and easy to update.

Practice

1. What does the @each loop do when used with a map in Sass?

easy

A. It creates a new map from the keys only.

B. It deletes all map entries after looping.

C. It repeats styles for each key-value pair in the map.

D. It converts the map into a list.

Solution

1. Step 1: Understand the purpose of @each with maps

   The @each loop iterates over each key-value pair in a map.

2. Step 2: Identify what happens during iteration

   For each pair, it repeats the block of styles or code inside the loop.

3. Final Answer:

   It repeats styles for each key-value pair in the map. -> Option C

4. Quick Check:

   @each loops over map pairs = repeats styles [OK]

Hint: Remember: @each repeats code for each map pair [OK]

Common Mistakes:

• Thinking @each deletes map entries
• Confusing map keys with list items
• Assuming it converts maps to lists

2. Which of the following is the correct syntax to loop over a map $colors with @each in Sass?

easy

A. @each $key $value in $colors { ... }

B. @each $colors in $key, $value { ... }

C. @each $value, $key in $colors { ... }

D. @each $key, $value in $colors { ... }

Solution

1. Step 1: Recall the correct @each syntax for maps

   The syntax requires two variables separated by a comma, then in, then the map name.

2. Step 2: Match the syntax to the options

   @each $key, $value in $colors { ... } correctly uses @each $key, $value in $colors. Others have wrong order or missing comma.

3. Final Answer:

   @each $key, $value in $colors { ... } -> Option D

4. Quick Check:

   Two variables separated by comma + in + map name [OK]

Hint: Use comma between key and value, then 'in' before map [OK]

Common Mistakes:

• Swapping key and value order
• Missing comma between variables
• Using wrong variable order or syntax

3. Given the Sass map and code:

$themes: (light: #fff, dark: #000); @each $name, $color in $themes { .#{$name}-theme { background: $color; } }

What CSS will this generate?

medium

A. .light-theme { background: #fff; } .dark-theme { background: #000; }

B. .light { background: #fff; } .dark { background: #000; }

C. .theme-light { background: #fff; } .theme-dark { background: #000; }

D. .light-theme { background: light; } .dark-theme { background: dark; }

Solution

1. Step 1: Understand the map and loop variables

   The map has keys light and dark with colors #fff and #000.

2. Step 2: Analyze the generated CSS selectors and properties

   The selector uses interpolation .#{$name}-theme producing .light-theme and .dark-theme. The background uses the color value.

3. Final Answer:

   .light-theme { background: #fff; } .dark-theme { background: #000; } -> Option A

4. Quick Check:

   Interpolation creates .light-theme and .dark-theme with correct colors [OK]

Hint: Interpolation with #{} creates dynamic class names [OK]

Common Mistakes:

• Forgetting interpolation syntax
• Using keys as colors instead of values
• Mixing up class name order

4. Identify the error in this Sass code:

$sizes: (small: 1rem, medium: 2rem); @each $size in $sizes { .btn-#{$size} { font-size: $size; } }

medium

A. Missing comma between key and value in @each loop.

B. Using only one variable for a map instead of two.

C. Incorrect interpolation syntax in class name.

D. Map keys and values are reversed.

Solution

1. Step 1: Check the @each loop variables

   The map has key-value pairs, so the loop needs two variables separated by a comma.

2. Step 2: Identify the problem with one variable

   The code uses only $size instead of $key, $value, so it cannot access both parts of the map.

3. Final Answer:

   Using only one variable for a map instead of two. -> Option B

4. Quick Check:

   Maps need two variables in @each loops [OK]

Hint: Use two variables for maps in @each loops [OK]

Common Mistakes:

• Using one variable for map iteration
• Forgetting comma between variables
• Misusing interpolation syntax

5. You have a Sass map:

$shadows: (none: 0 0 0 transparent, light: 0 1px 3px rgba(0,0,0,0.12), heavy: 0 4px 6px rgba(0,0,0,0.3));

Write a @each loop that creates classes .shadow-none, .shadow-light, and .shadow-heavy with the correct box-shadow property. Which code snippet is correct?

hard

A. @each $name, $shadow in $shadows { .shadow-#{$name} { box-shadow: $shadow; } }

B. @each $shadow, $name in $shadows { .shadow-#{$name} { box-shadow: $shadow; } }

C. @each $name in $shadows { .shadow-#{$name} { box-shadow: $name; } }

D. @each $name, $shadow in $shadows { .shadow-#{$shadow} { box-shadow: $name; } }

Solution

1. Step 1: Identify correct variable order for map iteration

   Maps use @each $key, $value in $map, so $name is key and $shadow is value.

2. Step 2: Check class name and property usage

   The class uses interpolation with the key $name, and the property uses the value $shadow.

3. Final Answer:

   @each $name, $shadow in $shadows { .shadow-#{$name} { box-shadow: $shadow; } } -> Option A

4. Quick Check:

   Key first, value second, use interpolation for class [OK]

Hint: Map loops: key first, value second, interpolate key for class [OK]

Common Mistakes:

• Swapping key and value variables
• Using only one variable for map
• Interpolating value instead of key in class name