@each loop over maps in SASS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the @each loop in Sass when used with maps?

The @each loop in Sass lets you go through each key-value pair in a map, so you can use those values to create styles dynamically.

beginner

How do you access the key and value inside an @each loop over a Sass map?

You write @each $key, $value in $map. This sets $key to the map's key and $value to its value for each loop cycle.

intermediate

Example: What does this Sass code do?

@each $color, $hex in $colors {
  .text-#{$color} {
    color: $hex;
  }
}

It creates CSS classes like .text-red or .text-blue with the text color set to the corresponding hex value from the $colors map.

intermediate

Can you use @each to loop over just the keys or just the values of a Sass map?

Yes! You can loop over just keys by using map-keys($map) or just values with map-values($map) inside the @each loop.

beginner

Why is using @each loop over maps helpful in real web design?

It helps keep your styles organized and easy to update. For example, changing a color in one place updates all related styles automatically.

What does @each $key, $value in $map do in Sass?

A Converts the map to a list

B Loops through each key-value pair in the map

C Deletes all keys in the map

D Creates a new map

The @each loop goes through each key and value in the map one by one.

How do you write a loop to get only the keys from a Sass map?

A @each $key in map-keys($map)

B @each $key in map-values($map)

C @each $value in $map

D @each $key, $value in $map

Using map-keys($map) returns only the keys, which you can loop over.

What will this Sass code generate?

$colors: (red: #f00, blue: #00f);
@each $name, $hex in $colors {
  .bg-#{$name} {
    background-color: $hex;
  }
}

A An error because maps can't be looped

B CSS classes .red and .blue with text colors

C Nothing, it's invalid syntax

D CSS classes .bg-red and .bg-blue with background colors

It creates classes with background colors from the map keys and values.

Which Sass function returns all values from a map?

A map-values()

B map-keys()

C map-get()

D map-remove()

map-values() returns a list of all values in the map.

Why is looping over maps with @each useful?

A It slows down the CSS rendering

B It deletes unused styles automatically

C It helps create repetitive styles easily and keeps code DRY

D It converts CSS to JavaScript

Looping helps write less code and update styles in one place.

Explain how to use the @each loop to create CSS classes from a Sass map of colors.

Think about how to turn map keys into class names and values into style values.

Describe the difference between looping over a map directly and looping over map-keys or map-values in Sass.

Consider what you want to access inside the loop.

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