@for loop (through vs to) in SASS - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create 4 boxes with different background colors using a @for loop that includes the last number.

SASS

@for $i from 1 [1] 4 {
  .box-#{$i} {
    background-color: lighten(blue, 10% * $i);
  }
}

Drag options to blanks, or click blank then click option'

Ato

Bthrough

Cuntil

Dupto

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'to' will stop before the last number, so only 3 boxes are created instead of 4.

Using 'through' includes the last number in the loop, so it runs from 1 to 4 including 4.

2fill in blank

medium

Complete the code to create 4 buttons with increasing padding using a @for loop that excludes the last number.

SASS

@for $j from 1 [1] 5 {
  .btn-#{$j} {
    padding: $j * 0.5rem;
  }
}

Drag options to blanks, or click blank then click option'

Ato

Bthrough

Cupto

Duntil

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'through' will include 5, creating an extra button.

Using 'to' excludes the last number, so the loop runs from 1 to 4.

3fill in blank

hard

Fix the error in the loop keyword to correctly generate 6 list items.

SASS

ul {
  @for $k from 1 [1] 6 {
    li:nth-child(#{$k}) {
      content: "Item #{$k}";
    }
  }
}

Drag options to blanks, or click blank then click option'

Ato

Buntil

Cupto

Dthrough

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'to' causes the loop to stop before 6, missing the last item.

'through' includes the last number 6, so the loop runs from 1 to 6.

4fill in blank

hard

Fill both blanks to create 4 colored squares with increasing size using a @for loop that excludes the last number.

SASS

@for $n from 1 [1] 5 {
  .square-#{$n} {
    width: $n * 2rem;
    height: $n * 2rem;
    background-color: adjust-hue(red, $n * 20deg);
  }
  @if $n [2] 3 {
    border: 1px solid black;
  }
}

Drag options to blanks, or click blank then click option'

Ato

Bthrough

C<=

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'through' includes 5, creating an extra square.

Using '<=' applies border to $n=3, which is not intended.

The loop uses 'to' to exclude 5, so it runs 1 to 4. The condition uses '<' to apply border only when $n is less than 3.

5fill in blank

hard

Fill all three blanks to create a list of 6 items with different font sizes and colors using a @for loop that includes the last number.

SASS

ol {
  @for $m from 1 [1] 6 {
    li:nth-child(#{$m}) {
      font-size: $m * 0.8rem;
      color: adjust-hue(blue, $m * [2]deg);
      margin-bottom: [3]rem;
    }
  }
}

Drag options to blanks, or click blank then click option'

Ato

Bthrough

C15

D1.2

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'to' excludes the last item.

Using too large or too small hue values causes poor color changes.

The loop uses 'through' to include 6, so it runs 1 to 6. The hue adjustment uses 15 degrees per step, and margin-bottom is set to 1.2 rem.

Practice

1. What is the main difference between @for $i from 1 through 5 and @for $i from 1 to 5 in Sass?

easy

A. through includes 5, to stops before 5

B. to includes 5, through stops before 5

C. Both include 5

D. Both stop before 5

Solution

1. Step 1: Understand through keyword

   The through keyword means the loop will include the last number in the range.

2. Step 2: Understand to keyword

   The to keyword means the loop stops before the last number, excluding it.

3. Final Answer:

   through includes 5, to stops before 5 -> Option A

4. Quick Check:

   through includes last number, to excludes last number [OK]

Hint: Remember: through = include last, to = exclude last [OK]

Common Mistakes:

• Confusing which keyword includes the last number
• Thinking both keywords behave the same
• Assuming to includes the last number

2. Which of the following is the correct syntax to loop from 1 up to but not including 5 in Sass?

easy

A. @for $i from 1 through 5 { }

B. @for $i in 1 to 5 { }

C. @for $i from 1 to 5 { }

D. @for $i from 1 until 5 { }

Solution

1. Step 1: Identify correct @for syntax

   The correct syntax uses @for $i from start to end or through.

2. Step 2: Choose syntax for excluding last number

   To exclude the last number, use to, so @for $i from 1 to 5 { } is correct.

3. Final Answer:

   @for $i from 1 to 5 { } -> Option C

4. Quick Check:

   Use to to exclude last number [OK]

Hint: Use 'to' to exclude last number in @for loop [OK]

Common Mistakes:

• Using 'through' when wanting to exclude last number
• Using 'in' instead of 'from'
• Using 'until' which is invalid in Sass

3. What CSS classes will be generated by this Sass code?

@for $i from 1 through 3 {
  .item-#{$i} {
    width: 10px * $i;
  }
}

medium

A. .item-1 { width: 10px; } .item-3 { width: 30px; }

B. .item-1 { width: 10px; } .item-2 { width: 20px; }

C. .item-1 { width: 10px; } .item-2 { width: 20px; } .item-3 { width: 10px; }

D. .item-1 { width: 10px; } .item-2 { width: 20px; } .item-3 { width: 30px; }

Solution

1. Step 1: Understand loop range with through

   The loop runs from 1 to 3 including 3, so $i = 1, 2, 3.

2. Step 2: Calculate width for each iteration

   Widths are 10px * 1 = 10px, 10px * 2 = 20px, 10px * 3 = 30px.

3. Final Answer:

   .item-1 { width: 10px; } .item-2 { width: 20px; } .item-3 { width: 30px; } -> Option D

4. Quick Check:

   Loop includes 3, widths multiply by $i [OK]

Hint: Remember 'through' includes last number, so 3 iterations [OK]

Common Mistakes:

• Thinking loop stops before 3
• Multiplying width incorrectly
• Missing last class .item-3

4. Identify the error in this Sass code:

@for $i from 1 to 4 {
  .box-#{$i} {
    height: 5px * $i;
  }
}

@for $j from 1 through 4
  .circle-#{$j} {
    width: 5px * $j;
  }

medium

A. Missing curly braces in second loop

B. Using through instead of to in second loop

C. Multiplication syntax is wrong

D. Variable names must be the same in both loops

Solution

1. Step 1: Check syntax of first loop

   The first loop uses correct syntax with curly braces around the block.

2. Step 2: Check syntax of second loop

   The second loop is missing curly braces after the loop declaration, which is required.

3. Final Answer:

   Missing curly braces in second loop -> Option A

4. Quick Check:

   Loops need curly braces for their blocks [OK]

Hint: Always use curly braces {} after @for loop declaration [OK]

Common Mistakes:

• Omitting curly braces after @for
• Confusing 'to' and 'through' keywords
• Incorrect multiplication syntax

5. You want to create 4 buttons with classes .btn-1 to .btn-4 using a Sass @for loop. Which loop should you use to include the last button class .btn-4?

hard

A. @for $i from 1 to 4 { ... }

B. @for $i from 1 through 4 { ... }

C. @for $i from 1 until 4 { ... }

D. @for $i from 1 to 5 { ... }

Solution

1. Step 1: Understand loop range needed

   You want classes from 1 to 4 inclusive, so the loop must include 4.

2. Step 2: Choose correct keyword to include last number

   Using through includes the last number, so @for $i from 1 through 4 is correct.

3. Final Answer:

   @for $i from 1 through 4 { ... } -> Option B

4. Quick Check:

   Use through to include last number [OK]

Hint: Use 'through' to include last number in loop [OK]

Common Mistakes:

• Using 'to' which excludes last number
• Using invalid keyword 'until'
• Using range that goes beyond needed number