freeCodeCamp Challenge Guide: Use @for to Create a Sass Loop

Use @for to Create a Sass Loop


Problem Explanation

  1. The basic syntax of @for loop in SASS:
  • For - through loop:
@for $i from <start number> through <end number> {
  // some CSS
}
  • For - to loop:
@for $i from <start number> to <end number> {
  // some CSS
}

Notice that the main difference is that “start to end” excludes the end number, and “start through end” includes the end number.
2. For example:

  • For - through loop:
@for $i from 1 through 3 {
  // some CSS
}

// 1 2 3
  • For - to loop:
@for $i from 1 to 3 {
  // some CSS
}

// 1 2
  1. Guideline from SASS Guideline

The @for loop might be useful when combined with CSS’ :nth-* pseudo-classes. Except for these scenarios, prefer an @each loop if you have to iterate over something.

@for $i from 1 through 10 {
  .foo:nth-of-type(#{$i}) {
    border-color: hsl($i * 36, 50%, 50%);
  }
}

Always use $i as a variable name to stick to the usual convention and unless you have a really good reason to, never use the to keyword: always use through. Many developers do not even know Sass offers this variation; using it might lead to confusion.

Also be sure to respect those guidelines to preserve readability:

  • Always an empty new line before @for;
  • Always an empty new line after the closing brace (}) unless the next line is a closing brace (}).

Solutions

Solution 1 (Click to Show/Hide)
<style type='text/scss'>
  @for $j from 1 through 5 {
    .text-#{$j} { font-size: 15px * $j; }
  }
</style>

<p class="text-1">Hello</p>
<p class="text-2">Hello</p>
<p class="text-3">Hello</p>
<p class="text-4">Hello</p>
<p class="text-5">Hello</p>

The solution above will generate the following CSS:

.text-1 {
  font-size: 15px;
}

.text-2 {
  font-size: 30px;
}

.text-3 {
  font-size: 45px;
}

.text-4 {
  font-size: 60px;
}

.text-5 {
  font-size: 75px;
}

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