Built-in map functions in SASS

Introduction

Built-in map functions help you work with groups of key-value pairs easily in Sass. They let you find, add, or change values without extra hassle.

When you want to store colors with names and use them later in your styles.

When you need to check if a certain setting exists before applying styles.

When you want to add new options to a list of settings without rewriting everything.

When you want to get all keys or values from a group to use in loops.

When you want to merge two groups of settings into one.

Syntax

SASS

$map: (key1: value1, key2: value2);

map.get($map, key1);
map.has-key($map, key1);
map.merge($map1, $map2);
map.keys($map);
map.values($map);

map.get gets the value for a key.

map.has-key checks if a key exists.

Examples

This gets the color for 'primary' from the map.

SASS

$colors: (primary: #333, secondary: #666);

$primary-color: map.get($colors, primary);

This checks if 'tertiary' color exists before using it.

SASS

@if map.has-key($colors, tertiary) {
  // do something
} @else {
  // fallback
}

This adds a new color to the existing colors map.

SASS

$new-colors: (tertiary: #999);
$all-colors: map.merge($colors, $new-colors);

This gets all keys and values separately from the map.

SASS

$keys: map.keys($colors);
$values: map.values($colors);

Sample Program

This Sass code creates a map of settings, gets and checks keys, adds a new key, and uses the values in CSS styles. It also shows how to get all keys and values.

SASS

@use 'sass:map';

$settings: (
  font-size: 1.2rem,
  color: #0055cc,
  margin: 1rem
);

// Get font size
$font-size: map.get($settings, font-size);

// Check if padding exists
$has-padding: map.has-key($settings, padding);

// Add padding
$new-settings: map.merge($settings, (padding: 2rem));

// Get all keys
$keys: map.keys($new-settings);

// Get all values
$values: map.values($new-settings);

body {
  font-size: $font-size;
  color: map.get($new-settings, color);
  margin: map.get($new-settings, margin);
  padding: map.get($new-settings, padding);
}

/* Keys: #{$keys} */
/* Values: #{$values} */

Important Notes

Maps in Sass are like labeled boxes where you keep pairs of names and values.

Use map.get to find a value by its name.

Always check if a key exists with map.has-key before using it to avoid errors.

Summary

Built-in map functions help manage key-value pairs in Sass easily.

You can get, check, add, and list keys and values with simple functions.

Using maps keeps your styles organized and flexible.

Practice

1. Which Sass built-in map function is used to check if a key exists in a map?
map-get(), map-has-key(), map-keys(), or map-values()?

easy

A. map-has-key()

B. map-get()

C. map-keys()

D. map-values()

Solution

1. Step 1: Understand the purpose of each function

   map-get() retrieves a value, map-keys() lists keys, map-values() lists values, and map-has-key() checks if a key exists.

2. Step 2: Identify the function that checks key existence

   The function map-has-key() returns true or false if a key is in the map.

3. Final Answer:

   map-has-key() -> Option A

4. Quick Check:

   Check key presence = map-has-key() [OK]

Hint: To check keys, use map-has-key() [OK]

Common Mistakes:

• Confusing map-get() with map-has-key()
• Using map-keys() to check key existence
• Thinking map-values() checks keys

2. Which of the following is the correct syntax to get the value for key "color" from a Sass map named $theme?

easy

A. map-get($theme, color)

B. map-get(color, $theme)

C. map-get($theme, $color)

D. map-get($theme, "color")

Solution

1. Step 1: Recall map-get() syntax

   The correct syntax is map-get($map, $key) where the key is a string or identifier.

2. Step 2: Identify correct key format

   Keys that are strings must be quoted with double or single quotes. Here, "color" is correct.

3. Final Answer:

   map-get($theme, "color") -> Option D

4. Quick Check:

   Correct syntax uses map-get($map, "key") [OK]

Hint: Use quotes around string keys in map-get() [OK]

Common Mistakes:

• Omitting quotes around string keys
• Swapping map and key order
• Using a variable ($color) instead of a quoted string key

3. Given the Sass map:

$settings: ("font": "Arial", "size": 16px, "color": #333);

What does map-keys($settings) return?

medium

A. ("font", "size", "color")

B. (font, size, color)

C. ["font", "size", "color"]

D. null

Solution

1. Step 1: Understand map-keys() output

   map-keys() returns a list of keys from the map, preserving quotes if keys are strings.

2. Step 2: Check keys in $settings

   Keys are strings: "font", "size", "color" so the output is a list with quoted strings.

3. Final Answer:

   ("font", "size", "color") -> Option A

4. Quick Check:

   map-keys() returns keys as list with quotes if keys are strings [OK]

Hint: map-keys() returns keys as a list with quotes if strings [OK]

Common Mistakes:

• Assuming keys lose quotes in output
• Confusing parentheses with brackets
• Expecting null or empty output

4. What is wrong with this Sass code?

$map: ("a": 1, "b": 2);
$value: map-get($map, c);

Choose the best explanation.

medium

A. map-get() cannot retrieve numeric values

B. Key c is missing quotes, causing an error

C. The map variable is not defined properly

D. map-get() requires three arguments

Solution

1. Step 1: Check map keys and usage

   The map keys are strings "a" and "b". The key used in map-get is c without quotes.

2. Step 2: Identify key type mismatch

   Since keys are strings, the key argument must be a string too. Missing quotes cause Sass to look for a variable c, which is undefined.

3. Final Answer:

   Key c is missing quotes, causing an error -> Option B

4. Quick Check:

   Keys must match type; string keys need quotes [OK]

Hint: Always quote string keys in map-get() [OK]

Common Mistakes:

• Forgetting quotes around string keys
• Thinking map-get needs 3 arguments
• Assuming map-get can't get numbers

5. You have a Sass map:

$colors: ("primary": #0055ff, "secondary": #ff5500, "tertiary": #00ff55);

Which Sass code correctly adds a new key-value pair "background": #f0f0f0 to $colors without overwriting existing keys?

hard

A. $new-colors: map-has-key($colors, "background", #f0f0f0);

B. $new-colors: map-get($colors, "background", #f0f0f0);

C. $new-colors: map-merge($colors, ("background": #f0f0f0));

D. $new-colors: map-keys($colors, "background": #f0f0f0);

Solution

1. Step 1: Understand how to add key-value pairs

   Sass maps are immutable, so to add a pair, use map-merge() which combines maps.

2. Step 2: Identify correct function usage

   map-merge($colors, ("background": #f0f0f0)) adds the new pair without removing existing ones.

3. Final Answer:

   $new-colors: map-merge($colors, ("background": #f0f0f0)); -> Option C

4. Quick Check:

   Use map-merge() to add keys without overwriting [OK]

Hint: Use map-merge() to add keys to Sass maps [OK]

Common Mistakes:

• Using map-get() to add keys
• Confusing map-has-key() with adding keys
• Trying to add keys with map-keys()